diff --git a/BattleTech-A-Time-of-War/BattleTech-A-Time-of-War.html b/BattleTech-A-Time-of-War/BattleTech-A-Time-of-War.html
index 008ca3305c..6d8c7101e9 100644
--- a/BattleTech-A-Time-of-War/BattleTech-A-Time-of-War.html
+++ b/BattleTech-A-Time-of-War/BattleTech-A-Time-of-War.html
@@ -517,6 +517,9 @@
 <!-- SKILLS -->
 <div class="tab-content tab3 main">
     <h3>Skills</h3>
+    <input type="radio" value="-1" name="attr_learning_speed" class="skills-labels">Fast Learner</input>
+    <input type="radio" value="1" name="attr_learning_speed" class="skills-labels">Slow Learner</input>
+    <input type="radio" value="0" name="attr_learning_speed" checked="true" class="skills-labels">None</input>
     <div class="skills-headings skills-container">
         <span class="skills skill skills-headings left">Skill</span>
         <span class="skills skills-skill-level">Lvl</span>
@@ -763,8 +766,10 @@
 on("sheet:opened", () => {
     sheetMigration();
 
-    getAttrs(["btatow_sheet_version"], values => {
-        if (values["btatow_sheet_version"] >= 3) {
+    getAttrs(["btatow_sheet_version"], ({
+        btatow_sheet_version
+    }) => {
+        if (btatow_sheet_version >= 3) {
             recalculateSkills();
         }
     });
@@ -775,7 +780,7 @@ const recalculateSkills = () => {
         ids.forEach(id => getAttrs(["repeating_skills_" + id + "_skill_xp"], values => {
             skillXPChanged({
                 newValue: values["repeating_skills_" + id + "_skill_xp"],
-                id: id
+                id
             })
         }));
     });
@@ -800,57 +805,67 @@ const CHARISMA_LINK = "charisma_link";
 const EDGE_LINK = "edge_link";
 
 // calculate stat values when XP amount changes
-on("change:strength_xp change:body_xp change:reflex_xp change:dexterity_xp change:intelligence_xp change:will_xp change:charisma_xp change:edge_xp", eventInfo => {
-    attributeName = eventInfo.sourceAttribute;
-
-    attributeValue = Math.floor(eventInfo.newValue/100);
+on("change:strength_xp change:body_xp change:reflex_xp change:dexterity_xp change:intelligence_xp change:will_xp change:charisma_xp change:edge_xp", ({
+    sourceAttribute,
+    newValue
+}) => {
+    attributeValue = Math.floor(newValue / 100);
     attributeLinkedValue = calculateLinkedAttributeValue(attributeValue);
 
     let attributesToSet = {};
 
-    switch (attributeName) {
-        case STRENGTH_XP: attributesToSet = {
-                            strength: attributeValue,
-                            strength_link: attributeLinkedValue
-                        };
-                        break;
-        case BODY_XP: attributesToSet = {
-                            body: attributeValue,
-                            body_link: attributeLinkedValue
-                        };
-                        break;
-        case REFLEX_XP: attributesToSet = {
-                            reflex: attributeValue,
-                            reflex_link: attributeLinkedValue
-                        };
-                        break;
-        case DEXTERITY_XP: attributesToSet = {
-                            dexterity: attributeValue,
-                            dexterity_link: attributeLinkedValue
-                        };
-                        break;
-        case INTELLIGENCE_XP: attributesToSet = {
-                            intelligence: attributeValue,
-                            intelligence_link: attributeLinkedValue
-                        };
-                        break;
-        case WILL_XP: attributesToSet = {
-                            will: attributeValue,
-                            will_link: attributeLinkedValue
-                        };
-                        break;
-        case CHARISMA_XP: attributesToSet = {
-                            charisma: attributeValue,
-                            charisma_link: attributeLinkedValue
-                        };
-                        break;
-        case EDGE_XP: attributesToSet = {
-                            edge: attributeValue,
-                            edge_link: attributeLinkedValue
-                        };
-                        break;
-        default: console.error("unknown attribute type passed in to basic attribute on change function");
-                        return;
+    switch (sourceAttribute) {
+    case STRENGTH_XP:
+        attributesToSet = {
+            strength: attributeValue,
+            strength_link: attributeLinkedValue
+        };
+        break;
+    case BODY_XP:
+        attributesToSet = {
+            body: attributeValue,
+            body_link: attributeLinkedValue
+        };
+        break;
+    case REFLEX_XP:
+        attributesToSet = {
+            reflex: attributeValue,
+            reflex_link: attributeLinkedValue
+        };
+        break;
+    case DEXTERITY_XP:
+        attributesToSet = {
+            dexterity: attributeValue,
+            dexterity_link: attributeLinkedValue
+        };
+        break;
+    case INTELLIGENCE_XP:
+        attributesToSet = {
+            intelligence: attributeValue,
+            intelligence_link: attributeLinkedValue
+        };
+        break;
+    case WILL_XP:
+        attributesToSet = {
+            will: attributeValue,
+            will_link: attributeLinkedValue
+        };
+        break;
+    case CHARISMA_XP:
+        attributesToSet = {
+            charisma: attributeValue,
+            charisma_link: attributeLinkedValue
+        };
+        break;
+    case EDGE_XP:
+        attributesToSet = {
+            edge: attributeValue,
+            edge_link: attributeLinkedValue
+        };
+        break;
+    default:
+        console.error("unknown attribute type passed in to basic attribute on change function");
+        return;
     }
 
     setAttrs(attributesToSet, {}, recalculateSkills)
@@ -858,7 +873,7 @@ on("change:strength_xp change:body_xp change:reflex_xp change:dexterity_xp chang
 
 function calculateLinkedAttributeValue(attribute) {
     if (attribute > 10) {
-        return Math.floor(attribute/3);
+        return Math.floor(attribute / 3);
     } else {
         if (attribute < 1)
             return -4;
@@ -875,16 +890,26 @@ function calculateLinkedAttributeValue(attribute) {
     }
 }
 
-on("change:repeating_skills:skill change:repeating_skills:sub_skill", eventInfo => {
-    getAttrs(["repeating_skills_skill_xp"], values => {
-        skillXPChanged({newValue: values["repeating_skills_skill_xp"]});
+on("change:repeating_skills:skill change:repeating_skills:sub_skill", _ => {
+    getAttrs(["repeating_skills_skill_xp"], ({
+        repeating_skills_skill_xp
+    }) => {
+        skillXPChanged({
+            newValue: repeating_skills_skill_xp
+        });
     });
 });
 
 // calculate skill modifiers when skill xp changes
-on("change:repeating_skills:skill_xp", skillXPChanged);
+on("change:repeating_skills:skill_xp", skillXPChanged)
 
-function skillXPChanged(eventInfo) {
+// recalculate all skills when learning speed modifier changes
+on("change:learning_speed", recalculateSkills)
+
+function skillXPChanged({
+    id,
+    newValue
+}) {
     const tieredSkills = [
         "art",
         "computers",
@@ -896,20 +921,20 @@ function skillXPChanged(eventInfo) {
 
     // When the sheet is opened, or data migrations are run, the skills are retrieved via ID, and thus must have their
     // ID included in the attribute name when setting attributes.
-    const id = eventInfo.id !== undefined ? eventInfo.id + "_" : ""
+    const skillId = id !== undefined ? id + "_" : ""
 
-    const skill = "repeating_skills_" + id + "skill";
-    const skillLevel = "repeating_skills_" + id + "skill_level";
-    const subSkillAttrName = "repeating_skills_" + id + "sub_skill";
+    const skill = "repeating_skills_" + skillId + "skill";
+    const skillLevel = "repeating_skills_" + skillId + "skill_level";
+    const subSkillAttrName = "repeating_skills_" + skillId + "sub_skill";
 
-    getAttrs([skill, subSkillAttrName], values => {
+    getAttrs([skill, subSkillAttrName, "learning_speed"], values => {
         const skillName = values[skill]
         const skillNameLookupKey = skillName.split("_")[0]
         const subSkill = values[subSkillAttrName]
 
         let skillAttributesToSet = {};
 
-        skillAttributesToSet[skillLevel] = calculateSkillLevel(Number(eventInfo.newValue), 0);
+        skillAttributesToSet[skillLevel] = calculateSkillLevel(Number(newValue), values.learning_speed);
 
         const skillData = getSkill(
             skillNameLookupKey,
@@ -917,22 +942,22 @@ function skillXPChanged(eventInfo) {
             tieredSkills.includes(skillNameLookupKey)
         );
 
-        skillAttributesToSet["repeating_skills_" + id + "skill_tnc"] = skillData.targetNumber + "/" + skillData.complexity;
-        skillAttributesToSet["repeating_skills_" + id + "target_number"] = skillData.targetNumber;
+        skillAttributesToSet["repeating_skills_" + skillId + "skill_tnc"] = skillData.targetNumber + "/" + skillData.complexity;
+        skillAttributesToSet["repeating_skills_" + skillId + "target_number"] = skillData.targetNumber;
 
         getAttrs(skillData.linkedAttributes, values => {
-            skillAttributesToSet["repeating_skills_" + id + "skill_modifier"] = Object.values(values)
+            skillAttributesToSet["repeating_skills_" + skillId + "skill_modifier"] = Object.values(values)
                 .reduce((total, num) => Number(total) + Number(num)) + Number(skillAttributesToSet[skillLevel]);
 
-            skillAttributesToSet["repeating_skills_" + id + "skill_linked_attributes"] = skillData.linkedAttributes
+            skillAttributesToSet["repeating_skills_" + skillId + "skill_linked_attributes"] = skillData.linkedAttributes
                 .map(linkAtr => getLinkedAttributeDisplayName(linkAtr) + " (" + values[linkAtr] + ")")
                 .join(" + ");
 
-            skillAttributesToSet["repeating_skills_" + id + "skill_roll_value"] =
+            skillAttributesToSet["repeating_skills_" + skillId + "skill_roll_value"] =
                 getSkillDisplayName(skillData, skillName, subSkill) + " Skill Check:\n" +
                 "Margin of Success: [[2d6 + @{skill_modifier}[MOD] - @{target_number}[TN]]]";
 
-            setAttrs(skillAttributesToSet);
+            setAttrs(skillAttributesToSet, {}, () => {});
         });
     });
 }
@@ -977,7 +1002,7 @@ function getSkillDisplayName(skill, skillDisplayNameKey, subSkill) {
 
 const skillsList = {
     "acrobatics": {
-        "linkedAttributes": [ REFLEX_LINK ],
+        "linkedAttributes": [REFLEX_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -987,7 +1012,7 @@ const skillsList = {
         }
     },
     "acting": {
-        "linkedAttributes": [ CHARISMA_LINK ],
+        "linkedAttributes": [CHARISMA_LINK],
         "targetNumber": 8,
         "complexity": "CB",
         "subSkills": false,
@@ -996,7 +1021,7 @@ const skillsList = {
         }
     },
     "administration": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, WILL_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1005,7 +1030,7 @@ const skillsList = {
         }
     },
     "animal": {
-        "linkedAttributes": [ WILL_LINK ],
+        "linkedAttributes": [WILL_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1016,7 +1041,7 @@ const skillsList = {
         }
     },
     "appraisal": {
-        "linkedAttributes": [ INTELLIGENCE_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK],
         "targetNumber": 8,
         "complexity": "CB",
         "subSkills": false,
@@ -1025,7 +1050,7 @@ const skillsList = {
         }
     },
     "archery": {
-        "linkedAttributes": [ DEXTERITY_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1034,7 +1059,7 @@ const skillsList = {
         }
     },
     "artillery": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, WILL_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1043,7 +1068,7 @@ const skillsList = {
         }
     },
     "career": {
-        "linkedAttributes": [ INTELLIGENCE_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": true,
@@ -1052,7 +1077,7 @@ const skillsList = {
         }
     },
     "climbing": {
-        "linkedAttributes": [ DEXTERITY_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1061,7 +1086,7 @@ const skillsList = {
         }
     },
     "communications": {
-        "linkedAttributes": [ INTELLIGENCE_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1072,7 +1097,7 @@ const skillsList = {
         }
     },
     "cryptography": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, WILL_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1081,7 +1106,7 @@ const skillsList = {
         }
     },
     "demolitions": {
-        "linkedAttributes": [ DEXTERITY_LINK, INTELLIGENCE_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1090,7 +1115,7 @@ const skillsList = {
         }
     },
     "disguise": {
-        "linkedAttributes": [ CHARISMA_LINK ],
+        "linkedAttributes": [CHARISMA_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1099,7 +1124,7 @@ const skillsList = {
         }
     },
     "driving": {
-        "linkedAttributes": [ REFLEX_LINK, DEXTERITY_LINK ],
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1110,7 +1135,7 @@ const skillsList = {
         }
     },
     "escape": {
-        "linkedAttributes": [ STRENGTH_LINK, DEXTERITY_LINK ],
+        "linkedAttributes": [STRENGTH_LINK, DEXTERITY_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1119,7 +1144,7 @@ const skillsList = {
         }
     },
     "forgery": {
-        "linkedAttributes": [ DEXTERITY_LINK, INTELLIGENCE_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1128,7 +1153,7 @@ const skillsList = {
         }
     },
     "gunnery": {
-        "linkedAttributes": [ REFLEX_LINK, DEXTERITY_LINK ],
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1145,7 +1170,7 @@ const skillsList = {
         }
     },
     "interrogation": {
-        "linkedAttributes": [ WILL_LINK, CHARISMA_LINK ],
+        "linkedAttributes": [WILL_LINK, CHARISMA_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1154,7 +1179,7 @@ const skillsList = {
         }
     },
     "investigation": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, WILL_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1163,7 +1188,7 @@ const skillsList = {
         }
     },
     "language": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, CHARISMA_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, CHARISMA_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": true,
@@ -1172,7 +1197,7 @@ const skillsList = {
         }
     },
     "leadership": {
-        "linkedAttributes": [ WILL_LINK, CHARISMA_LINK ],
+        "linkedAttributes": [WILL_LINK, CHARISMA_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1181,7 +1206,7 @@ const skillsList = {
         }
     },
     "medtech": {
-        "linkedAttributes": [ INTELLIGENCE_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1191,7 +1216,7 @@ const skillsList = {
         }
     },
     "navigation": {
-        "linkedAttributes": [ INTELLIGENCE_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1204,7 +1229,7 @@ const skillsList = {
         }
     },
     "negotiation": {
-        "linkedAttributes": [ CHARISMA_LINK ],
+        "linkedAttributes": [CHARISMA_LINK],
         "targetNumber": 8,
         "complexity": "CB",
         "subSkills": false,
@@ -1213,7 +1238,7 @@ const skillsList = {
         }
     },
     "perception": {
-        "linkedAttributes": [ INTELLIGENCE_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1222,7 +1247,7 @@ const skillsList = {
         }
     },
     "piloting": {
-        "linkedAttributes": [ REFLEX_LINK, DEXTERITY_LINK ],
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1239,7 +1264,7 @@ const skillsList = {
         }
     },
     "protocol": {
-        "linkedAttributes": [ WILL_LINK, CHARISMA_LINK ],
+        "linkedAttributes": [WILL_LINK, CHARISMA_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": true,
@@ -1248,7 +1273,7 @@ const skillsList = {
         }
     },
     "running": {
-        "linkedAttributes": [ REFLEX_LINK ],
+        "linkedAttributes": [REFLEX_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1257,7 +1282,7 @@ const skillsList = {
         }
     },
     "science": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, WILL_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": true,
@@ -1266,7 +1291,7 @@ const skillsList = {
         }
     },
     "security": {
-        "linkedAttributes": [ DEXTERITY_LINK, INTELLIGENCE_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1276,7 +1301,7 @@ const skillsList = {
         }
     },
     "sensor": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, WILL_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1285,7 +1310,7 @@ const skillsList = {
         }
     },
     "small": {
-        "linkedAttributes": [ DEXTERITY_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1294,7 +1319,7 @@ const skillsList = {
         }
     },
     "stealth": {
-        "linkedAttributes": [ REFLEX_LINK, INTELLIGENCE_LINK ],
+        "linkedAttributes": [REFLEX_LINK, INTELLIGENCE_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1303,7 +1328,7 @@ const skillsList = {
         }
     },
     "strategy": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, WILL_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1312,7 +1337,7 @@ const skillsList = {
         }
     },
     "streetwise": {
-        "linkedAttributes": [ CHARISMA_LINK ],
+        "linkedAttributes": [CHARISMA_LINK],
         "targetNumber": 8,
         "complexity": "CB",
         "subSkills": true,
@@ -1321,7 +1346,7 @@ const skillsList = {
         }
     },
     "support": {
-        "linkedAttributes": [ DEXTERITY_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1330,7 +1355,7 @@ const skillsList = {
         }
     },
     "surgery": {
-        "linkedAttributes": [ DEXTERITY_LINK, INTELLIGENCE_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1340,7 +1365,7 @@ const skillsList = {
         }
     },
     "survival": {
-        "linkedAttributes": [ BODY_LINK, INTELLIGENCE_LINK ],
+        "linkedAttributes": [BODY_LINK, INTELLIGENCE_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": true,
@@ -1349,7 +1374,7 @@ const skillsList = {
         }
     },
     "swimming": {
-        "linkedAttributes": [ STRENGTH_LINK ],
+        "linkedAttributes": [STRENGTH_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1358,7 +1383,7 @@ const skillsList = {
         }
     },
     "tactics": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, WILL_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1371,7 +1396,7 @@ const skillsList = {
         }
     },
     "technician": {
-        "linkedAttributes": [ DEXTERITY_LINK, INTELLIGENCE_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1387,7 +1412,7 @@ const skillsList = {
         }
     },
     "thrown": {
-        "linkedAttributes": [ DEXTERITY_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1397,7 +1422,7 @@ const skillsList = {
         }
     },
     "tracking": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, WILL_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1407,7 +1432,7 @@ const skillsList = {
         }
     },
     "training": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, CHARISMA_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, CHARISMA_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1416,7 +1441,7 @@ const skillsList = {
         }
     },
     "zero": {
-        "linkedAttributes": [ REFLEX_LINK ],
+        "linkedAttributes": [REFLEX_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1428,7 +1453,7 @@ const skillsList = {
 
 const tieredSkillsBasic = {
     "art": {
-        "linkedAttributes": [ DEXTERITY_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK],
         "targetNumber": 8,
         "complexity": "CB",
         "subSkills": true,
@@ -1437,7 +1462,7 @@ const tieredSkillsBasic = {
         }
     },
     "computers": {
-        "linkedAttributes": [ INTELLIGENCE_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK],
         "targetNumber": 8,
         "complexity": "CB",
         "subSkills": false,
@@ -1446,7 +1471,7 @@ const tieredSkillsBasic = {
         }
     },
     "interest": {
-        "linkedAttributes": [ INTELLIGENCE_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK],
         "targetNumber": 8,
         "complexity": "CB",
         "subSkills": true,
@@ -1455,7 +1480,7 @@ const tieredSkillsBasic = {
         }
     },
     "martial": {
-        "linkedAttributes": [ REFLEX_LINK ],
+        "linkedAttributes": [REFLEX_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1464,7 +1489,7 @@ const tieredSkillsBasic = {
         }
     },
     "melee": {
-        "linkedAttributes": [ DEXTERITY_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1473,7 +1498,7 @@ const tieredSkillsBasic = {
         }
     },
     "prestidigitation": {
-        "linkedAttributes": [ DEXTERITY_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK],
         "targetNumber": 7,
         "complexity": "SB",
         "subSkills": false,
@@ -1487,7 +1512,7 @@ const tieredSkillsBasic = {
 
 const tieredSkillsAdvanced = {
     "art": {
-        "linkedAttributes": [ DEXTERITY_LINK, INTELLIGENCE_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": true,
@@ -1496,7 +1521,7 @@ const tieredSkillsAdvanced = {
         }
     },
     "computers": {
-        "linkedAttributes": [ DEXTERITY_LINK, INTELLIGENCE_LINK ],
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": false,
@@ -1505,7 +1530,7 @@ const tieredSkillsAdvanced = {
         }
     },
     "interest": {
-        "linkedAttributes": [ INTELLIGENCE_LINK, WILL_LINK ],
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
         "targetNumber": 9,
         "complexity": "CA",
         "subSkills": true,
@@ -1514,7 +1539,7 @@ const tieredSkillsAdvanced = {
         }
     },
     "martial": {
-        "linkedAttributes": [ REFLEX_LINK, DEXTERITY_LINK ],
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1523,7 +1548,7 @@ const tieredSkillsAdvanced = {
         }
     },
     "melee": {
-        "linkedAttributes": [ REFLEX_LINK, DEXTERITY_LINK ],
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1532,7 +1557,7 @@ const tieredSkillsAdvanced = {
         }
     },
     "prestidigitation": {
-        "linkedAttributes": [ REFLEX_LINK, DEXTERITY_LINK ],
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
         "targetNumber": 8,
         "complexity": "SA",
         "subSkills": false,
@@ -1592,15 +1617,15 @@ function sheetMigration() {
             return;
         }
 
-        switch(sheetVersion) {
-            case 1:
-                migrateFrom1To2();
-                break;
-            case 2:
-                migrateFrom2To3();
-                break;
-            default:
-                break;
+        switch (sheetVersion) {
+        case 1:
+            migrateFrom1To2();
+            break;
+        case 2:
+            migrateFrom2To3();
+            break;
+        default:
+            break;
         }
     });
 }
@@ -1641,7 +1666,7 @@ function migrateFrom1To2() {
             }
         }
 
-        console.debug("New attributes: "+ JSON.stringify(newAttributes));
+        console.debug("New attributes: " + JSON.stringify(newAttributes));
 
         setAttrs(newAttributes, {}, () => {
             setAttrs({
@@ -1650,7 +1675,7 @@ function migrateFrom1To2() {
                 console.log("Sheet data migration completed");
             });
         });
-     });
+    });
 }
 
 // Migrate skills data from version 2 to version 3
@@ -1736,15 +1761,17 @@ function migrateFrom2To3() {
 
                 newSkillValues[newSkillDataNames.skill] = skillName;
                 if (displaySubSkill && oldSkillSubSkillName !== undefined) {
-                newSkillValues[newSkillDataNames.subSkill] = oldSkillSubSkillName;
-            }
+                    newSkillValues[newSkillDataNames.subSkill] = oldSkillSubSkillName;
+                }
                 newSkillValues[newSkillDataNames.xp] = oldSkillValues[oldSkillDataNames.xp];
 
                 setAttrs(newSkillValues, {}, () => {
                     skillsUpdated++;
 
                     if (skillsUpdated === ids.length) {
-                        setAttrs({btatow_sheet_version: 3}, {}, () => {
+                        setAttrs({
+                            btatow_sheet_version: 3
+                        }, {}, () => {
                             console.log("Sheet migrated from version 2 to version 3.");
                             recalculateSkills();
                         });
diff --git a/BattleTech-A-Time-of-War/development/.eslintrc b/BattleTech-A-Time-of-War/development/.eslintrc
new file mode 100644
index 0000000000..597ff9f5f9
--- /dev/null
+++ b/BattleTech-A-Time-of-War/development/.eslintrc
@@ -0,0 +1,10 @@
+{
+    "extends": "eslint:recommended",
+    "env": {
+        "es6": true
+    },
+    "parserOptions": {
+        "ecmaVersion": 6
+    },
+    "rules": {}
+}
\ No newline at end of file
diff --git a/BattleTech-A-Time-of-War/development/.jsbeautifyrc b/BattleTech-A-Time-of-War/development/.jsbeautifyrc
new file mode 100644
index 0000000000..9c3d8bfcbd
--- /dev/null
+++ b/BattleTech-A-Time-of-War/development/.jsbeautifyrc
@@ -0,0 +1,3 @@
+{
+    "jslint_happy": true
+}
\ No newline at end of file
diff --git a/BattleTech-A-Time-of-War/development/sheet-worker.js b/BattleTech-A-Time-of-War/development/sheet-worker.js
new file mode 100644
index 0000000000..a4c0f5f700
--- /dev/null
+++ b/BattleTech-A-Time-of-War/development/sheet-worker.js
@@ -0,0 +1,1019 @@
+// run any data migrations
+on("sheet:opened", () => {
+    sheetMigration();
+
+    getAttrs(["btatow_sheet_version"], ({
+        btatow_sheet_version
+    }) => {
+        if (btatow_sheet_version >= 3) {
+            recalculateSkills();
+        }
+    });
+});
+
+const recalculateSkills = () => {
+    getSectionIDs("skills", ids => {
+        ids.forEach(id => getAttrs(["repeating_skills_" + id + "_skill_xp"], values => {
+            skillXPChanged({
+                newValue: values["repeating_skills_" + id + "_skill_xp"],
+                id
+            })
+        }));
+    });
+}
+
+const STRENGTH_XP = "strength_xp";
+const BODY_XP = "body_xp";
+const REFLEX_XP = "reflex_xp";
+const DEXTERITY_XP = "dexterity_xp";
+const INTELLIGENCE_XP = "intelligence_xp";
+const WILL_XP = "will_xp";
+const CHARISMA_XP = "charisma_xp";
+const EDGE_XP = "edge_xp";
+
+const STRENGTH_LINK = "strength_link";
+const BODY_LINK = "body_link";
+const REFLEX_LINK = "reflex_link";
+const DEXTERITY_LINK = "dexterity_link";
+const INTELLIGENCE_LINK = "intelligence_link";
+const WILL_LINK = "will_link";
+const CHARISMA_LINK = "charisma_link";
+const EDGE_LINK = "edge_link";
+
+// calculate stat values when XP amount changes
+on("change:strength_xp change:body_xp change:reflex_xp change:dexterity_xp change:intelligence_xp change:will_xp change:charisma_xp change:edge_xp", ({
+    sourceAttribute,
+    newValue
+}) => {
+    attributeValue = Math.floor(newValue / 100);
+    attributeLinkedValue = calculateLinkedAttributeValue(attributeValue);
+
+    let attributesToSet = {};
+
+    switch (sourceAttribute) {
+    case STRENGTH_XP:
+        attributesToSet = {
+            strength: attributeValue,
+            strength_link: attributeLinkedValue
+        };
+        break;
+    case BODY_XP:
+        attributesToSet = {
+            body: attributeValue,
+            body_link: attributeLinkedValue
+        };
+        break;
+    case REFLEX_XP:
+        attributesToSet = {
+            reflex: attributeValue,
+            reflex_link: attributeLinkedValue
+        };
+        break;
+    case DEXTERITY_XP:
+        attributesToSet = {
+            dexterity: attributeValue,
+            dexterity_link: attributeLinkedValue
+        };
+        break;
+    case INTELLIGENCE_XP:
+        attributesToSet = {
+            intelligence: attributeValue,
+            intelligence_link: attributeLinkedValue
+        };
+        break;
+    case WILL_XP:
+        attributesToSet = {
+            will: attributeValue,
+            will_link: attributeLinkedValue
+        };
+        break;
+    case CHARISMA_XP:
+        attributesToSet = {
+            charisma: attributeValue,
+            charisma_link: attributeLinkedValue
+        };
+        break;
+    case EDGE_XP:
+        attributesToSet = {
+            edge: attributeValue,
+            edge_link: attributeLinkedValue
+        };
+        break;
+    default:
+        console.error("unknown attribute type passed in to basic attribute on change function");
+        return;
+    }
+
+    setAttrs(attributesToSet, {}, recalculateSkills)
+});
+
+function calculateLinkedAttributeValue(attribute) {
+    if (attribute > 10) {
+        return Math.floor(attribute / 3);
+    } else {
+        if (attribute < 1)
+            return -4;
+        else if (attribute < 2)
+            return -2;
+        else if (attribute < 4)
+            return -1;
+        else if (attribute < 7)
+            return 0;
+        else if (attribute < 10)
+            return 1;
+        else
+            return 2;
+    }
+}
+
+on("change:repeating_skills:skill change:repeating_skills:sub_skill", _ => {
+    getAttrs(["repeating_skills_skill_xp"], ({
+        repeating_skills_skill_xp
+    }) => {
+        skillXPChanged({
+            newValue: repeating_skills_skill_xp
+        });
+    });
+});
+
+// calculate skill modifiers when skill xp changes
+on("change:repeating_skills:skill_xp", skillXPChanged)
+
+// recalculate all skills when learning speed modifier changes
+on("change:learning_speed", recalculateSkills)
+
+function skillXPChanged({
+    id,
+    newValue
+}) {
+    const tieredSkills = [
+        "art",
+        "computers",
+        "interest",
+        "martial",
+        "melee",
+        "prestidigitation"
+    ];
+
+    // When the sheet is opened, or data migrations are run, the skills are retrieved via ID, and thus must have their
+    // ID included in the attribute name when setting attributes.
+    const skillId = id !== undefined ? id + "_" : ""
+
+    const skill = "repeating_skills_" + skillId + "skill";
+    const skillLevel = "repeating_skills_" + skillId + "skill_level";
+    const subSkillAttrName = "repeating_skills_" + skillId + "sub_skill";
+
+    getAttrs([skill, subSkillAttrName, "learning_speed"], values => {
+        const skillName = values[skill]
+        const skillNameLookupKey = skillName.split("_")[0]
+        const subSkill = values[subSkillAttrName]
+
+        let skillAttributesToSet = {};
+
+        skillAttributesToSet[skillLevel] = calculateSkillLevel(Number(newValue), values.learning_speed);
+
+        const skillData = getSkill(
+            skillNameLookupKey,
+            skillAttributesToSet[skillLevel],
+            tieredSkills.includes(skillNameLookupKey)
+        );
+
+        skillAttributesToSet["repeating_skills_" + skillId + "skill_tnc"] = skillData.targetNumber + "/" + skillData.complexity;
+        skillAttributesToSet["repeating_skills_" + skillId + "target_number"] = skillData.targetNumber;
+
+        getAttrs(skillData.linkedAttributes, values => {
+            skillAttributesToSet["repeating_skills_" + skillId + "skill_modifier"] = Object.values(values)
+                .reduce((total, num) => Number(total) + Number(num)) + Number(skillAttributesToSet[skillLevel]);
+
+            skillAttributesToSet["repeating_skills_" + skillId + "skill_linked_attributes"] = skillData.linkedAttributes
+                .map(linkAtr => getLinkedAttributeDisplayName(linkAtr) + " (" + values[linkAtr] + ")")
+                .join(" + ");
+
+            skillAttributesToSet["repeating_skills_" + skillId + "skill_roll_value"] =
+                getSkillDisplayName(skillData, skillName, subSkill) + " Skill Check:\n" +
+                "Margin of Success: [[2d6 + @{skill_modifier}[MOD] - @{target_number}[TN]]]";
+
+            setAttrs(skillAttributesToSet, {}, () => {});
+        });
+    });
+}
+
+function calculateSkillLevel(skillXP, learningSpeedModifier) {
+    skillXP = Number(skillXP);
+    learningSpeedModifier = Number(learningSpeedModifier);
+
+    if (skillXP < (30 + (learningSpeedModifier * 3))) {
+        return 0;
+    }
+
+    if (skillXP >= (570 + (learningSpeedModifier * 57))) {
+        return 10;
+    }
+
+    let currentSkillXP = skillXP - (20 + (learningSpeedModifier * 2));
+
+    for (i = 1; i < 11; i++) {
+        if (currentSkillXP < i * (10 + learningSpeedModifier)) {
+            return i - 1;
+        }
+
+        currentSkillXP -= (i * (10 + learningSpeedModifier));
+    }
+
+    console.error("should never hit this line, this means the skill XP is not less than level 1, not greater than level 10, but also not within a level range.");
+    return undefined;
+}
+
+function getSkillDisplayName(skill, skillDisplayNameKey, subSkill) {
+    if (skill.subSkills === true) {
+        return skill.displayName[skillDisplayNameKey] + "/" + subSkill;
+    }
+
+    if (typeof subSkill === "string" && subSkill != "") {
+        return skill.displayName[skillDisplayNameKey] + " (" + subSkill + ")";
+    }
+
+    return skill.displayName[skillDisplayNameKey];
+}
+
+const skillsList = {
+    "acrobatics": {
+        "linkedAttributes": [REFLEX_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "acrobatics_free_fall": "Acrobatics/Free-Fall",
+            "acrobatics_gymnastics": "Acrobatics/Gymnastics"
+        }
+    },
+    "acting": {
+        "linkedAttributes": [CHARISMA_LINK],
+        "targetNumber": 8,
+        "complexity": "CB",
+        "subSkills": false,
+        "displayName": {
+            "acting": "Acting"
+        }
+    },
+    "administration": {
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "administration": "Administration"
+        }
+    },
+    "animal": {
+        "linkedAttributes": [WILL_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "animal_handling_herding": "Animal Handling/Herding",
+            "animal_handling_riding": "Animal Handling/Riding",
+            "animal_handling_training": "Animal Handling/Training"
+        }
+    },
+    "appraisal": {
+        "linkedAttributes": [INTELLIGENCE_LINK],
+        "targetNumber": 8,
+        "complexity": "CB",
+        "subSkills": false,
+        "displayName": {
+            "appraisal": "Appraisal"
+        }
+    },
+    "archery": {
+        "linkedAttributes": [DEXTERITY_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "archery": "Archery"
+        }
+    },
+    "artillery": {
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "artillery": "Artillery"
+        }
+    },
+    "career": {
+        "linkedAttributes": [INTELLIGENCE_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": true,
+        "displayName": {
+            "career": "Career"
+        }
+    },
+    "climbing": {
+        "linkedAttributes": [DEXTERITY_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "climbing": "Climbing"
+        }
+    },
+    "communications": {
+        "linkedAttributes": [INTELLIGENCE_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "communications_black_box": "Communications/Black Box",
+            "communications_conventional_em": "Communications/Conventional (EM)",
+            "communications_hyperpulse_generator": "Communications/Hyperpulse Generator"
+        }
+    },
+    "cryptography": {
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "cryptography": "Cryptography"
+        }
+    },
+    "demolitions": {
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "demolitions": "Demolitions"
+        }
+    },
+    "disguise": {
+        "linkedAttributes": [CHARISMA_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "disguise": "Disguise"
+        }
+    },
+    "driving": {
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "driving_ground_vehicles": "Driving/Ground Vehicles",
+            "driving_rail_vehicles": "Driving/Rail Vehicles",
+            "driving_sea_vehicles": "Driving/Sea Vehicles"
+        }
+    },
+    "escape": {
+        "linkedAttributes": [STRENGTH_LINK, DEXTERITY_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "escape_artist": "Escape Artist"
+        }
+    },
+    "forgery": {
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "forgery": "Forgery"
+        }
+    },
+    "gunnery": {
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "gunnery_aerospace": "Gunnery/Aerospace",
+            "gunnery_air_vehicle": "Gunnery/Air Vehicle",
+            "gunnery_battlesuit": "Gunnery/Battlesuit",
+            "gunnery_ground_vehicle": "Gunnery/Ground Vehicle",
+            "gunnery_mech": "Gunnery/'Mech",
+            "gunnery_protomech": "Gunnery/ProtoMech",
+            "gunnery_sea_vehicle": "Gunnery/Sea Vehicle",
+            "gunnery_spacecraft": "Gunnery/Spacecraft",
+            "gunnery_turret": "Gunnery/Turret"
+        }
+    },
+    "interrogation": {
+        "linkedAttributes": [WILL_LINK, CHARISMA_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "interrogation": "Interrogation"
+        }
+    },
+    "investigation": {
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "investigation": "Investigation"
+        }
+    },
+    "language": {
+        "linkedAttributes": [INTELLIGENCE_LINK, CHARISMA_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": true,
+        "displayName": {
+            "language": "Language"
+        }
+    },
+    "leadership": {
+        "linkedAttributes": [WILL_LINK, CHARISMA_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "leadership": "Leadership"
+        }
+    },
+    "medtech": {
+        "linkedAttributes": [INTELLIGENCE_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "medtech_general": "MedTech/General",
+            "medtech_veterinary": "MedTech/Veterinary"
+        }
+    },
+    "navigation": {
+        "linkedAttributes": [INTELLIGENCE_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "navigation_air": "Navigation/Air",
+            "navigation_ground": "Navigation/Ground",
+            "navigation_kf_jump": "Navigation/K-F Jump",
+            "navigation_sea": "Navigation/Sea",
+            "navigation_space": "Navigation/Space"
+        }
+    },
+    "negotiation": {
+        "linkedAttributes": [CHARISMA_LINK],
+        "targetNumber": 8,
+        "complexity": "CB",
+        "subSkills": false,
+        "displayName": {
+            "negotiation": "Negotiation"
+        }
+    },
+    "perception": {
+        "linkedAttributes": [INTELLIGENCE_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "perception": "Perception"
+        }
+    },
+    "piloting": {
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "piloting_aerospace": "Piloting/Aerospace",
+            "piloting_air_vehicle": "Piloting/Air Vehicle",
+            "piloting_battlesuit": "Piloting/Battlesuit",
+            "piloting_ground_vehicle": "Piloting/Ground Vehicle",
+            "piloting_mech": "Piloting/'Mech",
+            "piloting_protomech": "Piloting/ProtoMech",
+            "piloting_rail_vehicle": "Piloting/Rail Vehicle",
+            "piloting_sea_vehicle": "Piloting/Sea Vehicle",
+            "piloting_spacecraft": "Piloting/Spacecraft"
+        }
+    },
+    "protocol": {
+        "linkedAttributes": [WILL_LINK, CHARISMA_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": true,
+        "displayName": {
+            "protocol": "Protocol"
+        }
+    },
+    "running": {
+        "linkedAttributes": [REFLEX_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "running": "Running"
+        }
+    },
+    "science": {
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": true,
+        "displayName": {
+            "science": "Science"
+        }
+    },
+    "security": {
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "security_systems_electronic": "Security Systems/Electronic",
+            "security_systems_mechanical": "Security Systems/Mechanical"
+        }
+    },
+    "sensor": {
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "sensor_operations": "Sensor Operations"
+        }
+    },
+    "small": {
+        "linkedAttributes": [DEXTERITY_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "small_arms": "Small Arms"
+        }
+    },
+    "stealth": {
+        "linkedAttributes": [REFLEX_LINK, INTELLIGENCE_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "stealth": "Stealth"
+        }
+    },
+    "strategy": {
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "strategy": "Strategy"
+        }
+    },
+    "streetwise": {
+        "linkedAttributes": [CHARISMA_LINK],
+        "targetNumber": 8,
+        "complexity": "CB",
+        "subSkills": true,
+        "displayName": {
+            "streetwise": "Streetwise"
+        }
+    },
+    "support": {
+        "linkedAttributes": [DEXTERITY_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "support_weapons": "Support Weapons"
+        }
+    },
+    "surgery": {
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "surgery_general": "Surgery/General",
+            "surgery_veterinary": "Surgery/Veterinary"
+        }
+    },
+    "survival": {
+        "linkedAttributes": [BODY_LINK, INTELLIGENCE_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": true,
+        "displayName": {
+            "survival": "Survival"
+        }
+    },
+    "swimming": {
+        "linkedAttributes": [STRENGTH_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "swimming": "Swimming"
+        }
+    },
+    "tactics": {
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "tactics_air": "Tactics/Air",
+            "tactics_infantry": "Tactics/Infantry",
+            "tactics_land": "Tactics/Land",
+            "tactics_sea": "Tactics/Sea",
+            "tactics_space": "Tactics/Space"
+        }
+    },
+    "technician": {
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "technician_aeronautics": "Technician/Aeronautics",
+            "technician_cybernetics": "Technician/Cybernetics",
+            "technician_electronic": "Technician/Electronic",
+            "technician_jets": "Technician/Jets",
+            "technician_mechanical": "Technician/Mechanical",
+            "technician_myomer": "Technician/Myomer",
+            "technician_nuclear": "Technician/Nuclear",
+            "technician_weapons": "Technician/Weapons"
+        }
+    },
+    "thrown": {
+        "linkedAttributes": [DEXTERITY_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "thrown_weapons_blades": "Thrown Weapons/Blades",
+            "thrown_weapons_blunt_weapons": "Thrown Weapons/Blunt Weapons"
+        }
+    },
+    "tracking": {
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "tracking_urban": "Tracking/Urban",
+            "tracking_wilds": "Tracking/Wilds"
+        }
+    },
+    "training": {
+        "linkedAttributes": [INTELLIGENCE_LINK, CHARISMA_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "training": "Training"
+        }
+    },
+    "zero": {
+        "linkedAttributes": [REFLEX_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "zero_g_operations": "Zero-G Operations"
+        }
+    }
+};
+
+const tieredSkillsBasic = {
+    "art": {
+        "linkedAttributes": [DEXTERITY_LINK],
+        "targetNumber": 8,
+        "complexity": "CB",
+        "subSkills": true,
+        "displayName": {
+            "art": "Art"
+        }
+    },
+    "computers": {
+        "linkedAttributes": [INTELLIGENCE_LINK],
+        "targetNumber": 8,
+        "complexity": "CB",
+        "subSkills": false,
+        "displayName": {
+            "computers": "Computers"
+        }
+    },
+    "interest": {
+        "linkedAttributes": [INTELLIGENCE_LINK],
+        "targetNumber": 8,
+        "complexity": "CB",
+        "subSkills": true,
+        "displayName": {
+            "interest": "Interest"
+        }
+    },
+    "martial": {
+        "linkedAttributes": [REFLEX_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "martial_arts": "Martial Arts"
+        }
+    },
+    "melee": {
+        "linkedAttributes": [DEXTERITY_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "melee_weapons": "Melee Weapons"
+        }
+    },
+    "prestidigitation": {
+        "linkedAttributes": [DEXTERITY_LINK],
+        "targetNumber": 7,
+        "complexity": "SB",
+        "subSkills": false,
+        "displayName": {
+            "prestidigitation_pick_pocket": "Prestidigitation/Pick Pocket",
+            "prestidigitation_quickdraw": "Prestidigitation/Quickdraw",
+            "prestidigitation_sleight_of_hand": "Prestidigitation/Sleight of Hand"
+        }
+    }
+};
+
+const tieredSkillsAdvanced = {
+    "art": {
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": true,
+        "displayName": {
+            "art": "Art"
+        }
+    },
+    "computers": {
+        "linkedAttributes": [DEXTERITY_LINK, INTELLIGENCE_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": false,
+        "displayName": {
+            "computers": "Computers"
+        }
+    },
+    "interest": {
+        "linkedAttributes": [INTELLIGENCE_LINK, WILL_LINK],
+        "targetNumber": 9,
+        "complexity": "CA",
+        "subSkills": true,
+        "displayName": {
+            "interest": "Interest"
+        }
+    },
+    "martial": {
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "martial_arts": "Martial Arts"
+        }
+    },
+    "melee": {
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "melee_weapons": "Melee Weapons"
+        }
+    },
+    "prestidigitation": {
+        "linkedAttributes": [REFLEX_LINK, DEXTERITY_LINK],
+        "targetNumber": 8,
+        "complexity": "SA",
+        "subSkills": false,
+        "displayName": {
+            "prestidigitation_pick_pocket": "Prestidigitation/Pick Pocket",
+            "prestidigitation_quickdraw": "Prestidigitation/Quickdraw",
+            "prestidigitation_sleight_of_hand": "Prestidigitation/Sleight of Hand"
+        }
+    }
+};
+
+function getSkill(skillName, skillLevel, tieredSkill) {
+    skillName = String(skillName);
+    skillLevel = Number(skillLevel);
+
+    if (tieredSkill) {
+        if (skillLevel <= 3) {
+            return tieredSkillsBasic[skillName]
+        } else {
+            return tieredSkillsAdvanced[skillName]
+        }
+    } else {
+        return skillsList[skillName]
+    }
+}
+
+function getLinkedAttributeDisplayName(linkedAttributeName) {
+    const linkedAttributeDisplayNames = {};
+    linkedAttributeDisplayNames[STRENGTH_LINK] = "STR";
+    linkedAttributeDisplayNames[BODY_LINK] = "BOD";
+    linkedAttributeDisplayNames[REFLEX_LINK] = "RFL";
+    linkedAttributeDisplayNames[DEXTERITY_LINK] = "DEX";
+    linkedAttributeDisplayNames[INTELLIGENCE_LINK] = "INT";
+    linkedAttributeDisplayNames[WILL_LINK] = "WIL";
+    linkedAttributeDisplayNames[CHARISMA_LINK] = "CHA";
+    linkedAttributeDisplayNames[EDGE_LINK] = "EDG";
+
+    return linkedAttributeDisplayNames[linkedAttributeName];
+}
+
+function sheetMigration() {
+    console.log("Running sheet data migration");
+
+    let sheetVersionAttributeName = "btatow_sheet_version";
+    let currentVersion = 3;
+
+    getAttrs([sheetVersionAttributeName], sheetVersionAttribute => {
+        let sheetVersion = Number(sheetVersionAttribute[sheetVersionAttributeName])
+        // Check if we should do the migration
+        if (isNaN(sheetVersion)) {
+            console.error("No sheet version defined, unable to determine if sheet data needs to be migrated.");
+            return;
+        }
+
+        if (sheetVersion === currentVersion) {
+            console.log("No migration needed");
+            return;
+        }
+
+        switch (sheetVersion) {
+        case 1:
+            migrateFrom1To2();
+            break;
+        case 2:
+            migrateFrom2To3();
+            break;
+        default:
+            break;
+        }
+    });
+}
+
+// Migrate attribute data from version 1 to version 2
+function migrateFrom1To2() {
+    const oldAttributeNames = [
+        "STRXP",
+        "BODXP",
+        "RFLXP",
+        "DEXXP",
+        "INTXP",
+        "WILXP",
+        "CHAXP",
+        "EDGXP"
+    ];
+    const newAttributeNames = [
+        "strength_xp",
+        "body_xp",
+        "reflex_xp",
+        "dexterity_xp",
+        "intelligence_xp",
+        "will_xp",
+        "charisma_xp",
+        "edge_xp"
+    ];
+
+    let newAttributes = {};
+
+    console.log("Starting migration from version 1 to version 2.");
+
+    getAttrs(oldAttributeNames, attributes => {
+        console.debug("Attributes fetched: " + JSON.stringify(attributes));
+        for (let i = 0; i < oldAttributeNames.length; i++) {
+            if (attributes[oldAttributeNames[i]] !== undefined) {
+                console.debug("Attributes[" + oldAttributeNames[i] + "]: " + attributes[oldAttributeNames[i]]);
+                newAttributes[newAttributeNames[i]] = attributes[oldAttributeNames[i]];
+            }
+        }
+
+        console.debug("New attributes: " + JSON.stringify(newAttributes));
+
+        setAttrs(newAttributes, {}, () => {
+            setAttrs({
+                btatow_sheet_version: "2"
+            }, {}, () => {
+                console.log("Sheet data migration completed");
+            });
+        });
+    });
+}
+
+// Migrate skills data from version 2 to version 3
+function migrateFrom2To3() {
+    console.log("Starting migration from version 2 to version 3.");
+
+    getSectionIDs("skills", ids => {
+        let skillsUpdated = 0;
+
+        ids.forEach(id => {
+            const oldSkillDataNames = {
+                skill: "repeating_skills_" + id + "_skill",
+                subSkill: "repeating_skills_" + id + "_skillNotes",
+                xp: "repeating_skills_" + id + "_skillXP"
+            };
+            const newSkillDataNames = {
+                skill: "repeating_skills_" + id + "_skill",
+                subSkill: "repeating_skills_" + id + "_sub_skill",
+                xp: "repeating_skills_" + id + "_skill_xp"
+            };
+            getAttrs(Object.values(oldSkillDataNames), oldSkillValues => {
+                const oldSkillName = oldSkillValues[oldSkillDataNames.skill];
+                const oldSkillSubSkillName = oldSkillValues[oldSkillDataNames.subSkill];
+
+                if (oldSkillName === undefined || oldSkillValues[oldSkillDataNames.xp] === undefined) {
+                    console.error("Old skill data is missing values, unable to migrate.\n" + JSON.stringify(oldSkillValues));
+                    skillsUpdate++;
+                    return;
+                }
+
+                let parsedSkillName = oldSkillName.toLowerCase()
+                    .replace(" ", "_")
+                    .replace("-", "_");
+
+                const skillFirstName = parsedSkillName.split("_")[0];
+
+                let skillData = {};
+                const newSkillValues = {};
+
+                if (skillFirstName in skillsList) {
+                    skillData = skillsList[skillFirstName];
+                } else if (skillFirstName in tieredSkillsBasic) {
+                    skillData = tieredSkillsBasic[skillFirstName];
+                } else if (skillFirstName.substring(0, skillFirstName.length - 1) in tieredSkillsBasic) {
+                    skillData = tieredSkillsBasic[skillFirstName.substring(0, skillFirstName.length - 1)];
+                    parsedSkillName = parsedSkillName.substring(0, parsedSkillName.length - 1);
+                } else {
+                    console.error("Unable to migrate skill data. Old values are: " + JSON.stringify(oldSkillValues));
+                    skillsUpdated++;
+                    return;
+                }
+
+                let skillName = "";
+                let displaySubSkill = true;
+
+                if (parsedSkillName in skillData.displayName) {
+                    skillName = parsedSkillName;
+                } else if (parsedSkillName.substring(0, parsedSkillName.length - 1) in skillData.displayName) {
+                    skillName = parsedSkillName.substring(0, parsedSkillName.length - 1);
+                } else if (oldSkillSubSkillName === undefined) {
+                    console.error("Unable to identify skill. Old skill name: " + oldSkillName);
+                    skillsUpdated++;
+                    return;
+                } else {
+                    const parsedSubSkillName = oldSkillSubSkillName.trim()
+                        .replace("\'", "")
+                        .replace("`", "")
+                        .replace("-", "_")
+                        .replace("/", "_")
+                        .toLowerCase();
+
+                    const skillWithSubSkill = parsedSkillName + "_" + parsedSubSkillName;
+
+                    if (skillWithSubSkill in skillData.displayName) {
+                        skillName = skillWithSubSkill;
+                        displaySubSkill = false;
+                    } else {
+                        console.error("Unable to identify skill. Old skill name and notes: " + oldSkillName + " " + oldSkillSubSkillName);
+                        skillsUpdated++;
+                        return;
+                    }
+                }
+
+                newSkillValues[newSkillDataNames.skill] = skillName;
+                if (displaySubSkill && oldSkillSubSkillName !== undefined) {
+                    newSkillValues[newSkillDataNames.subSkill] = oldSkillSubSkillName;
+                }
+                newSkillValues[newSkillDataNames.xp] = oldSkillValues[oldSkillDataNames.xp];
+
+                setAttrs(newSkillValues, {}, () => {
+                    skillsUpdated++;
+
+                    if (skillsUpdated === ids.length) {
+                        setAttrs({
+                            btatow_sheet_version: 3
+                        }, {}, () => {
+                            console.log("Sheet migrated from version 2 to version 3.");
+                            recalculateSkills();
+                        });
+                    }
+                });
+            });
+        });
+    });
+}
\ No newline at end of file