followed suggestions of Copilot review.

Author: odungern

src/common/lib/helpers.ts

@@ -13,10 +13,10 @@
  *  -
  *
  *  @ToDo:
- *  -
+ *  - Resolve circular dependency between helpers.ts and pig-metaclasses.ts (IIdentifiable)
  */
 
-import { IIdentifiable } from '../schema/pig/ts/pig-metaclasses';
+import type { IIdentifiable } from '../schema/pig/ts/pig-metaclasses';
 import { DEF } from './definitions';
 
 /**

src/common/lib/revision-tracker.ts

@@ -65,7 +65,8 @@ export class RevisionTracker {
     static updateWithRevision<T extends IIdentifiable>(newElement: T, existingElement: T): T {
         const newRevision = this.makeRevision();
         const priorRev: string[] = [];
-        
+
+        // priorRevision shall remember the revision of the existing element. Usually there is one entry and two in case of a merge.
         if (existingElement.revision) {
             priorRev.push(existingElement.revision);
         }

src/common/schema/pig/ts/pig-metaclasses.ts

@@ -895,7 +895,7 @@ abstract class AnElement extends Identifiable implements IAnElement {
 
                         // Add the property with the key as its hasClass reference
                         if (itemTypeValue === PigItemType.aProperty /* || !itemTypeValue*/) {
-                            if (item.value || item.composes) {
+                            if (item.value !== undefined || item.composes) {
                                 configurables.push({
                                     itemType: PigItemType.aProperty,
                                     hasClass: key,
@@ -914,7 +914,7 @@ abstract class AnElement extends Identifiable implements IAnElement {
                 const itemTypeValue = val.itemType /* || (val[nameItemType] && extractId(val[nameItemType])) */;
 
                 if (itemTypeValue === PigItemType.aProperty /* || !itemTypeValue */) {
-                    if (val.value || val.composes) {
+                    if (val.value !== undefined || val.composes) {
                         configurables.push({
                             itemType: PigItemType.aProperty,
                             hasClass: key,
@@ -926,7 +926,7 @@ abstract class AnElement extends Identifiable implements IAnElement {
                 }
             }
             // Handle primitive values (string, number, boolean) - create simple properties
-            else if (val && (typeof val === 'string' || typeof val === 'number' || typeof val === 'boolean')) {
+            else if (val !== undefined && val !== null && (typeof val === 'string' || typeof val === 'number' || typeof val === 'boolean')) {
                 configurables.push({
                     itemType: PigItemType.aProperty,
                     hasClass: key,

src/plugins/export/ttl/export-ttl.vue

@@ -109,7 +109,7 @@ import { LIB, LOG } from '../../../common/lib/helpers';
         options: {
             skipShapes: false,              // Will be negated to addShapes: true
             skipHostedOntologies: false,    // Will be negated to addHostedOntologies: true
-            addExplicitSubTypes: false,     // Passed as-is (false = don't add)
+            addExplicitTypeToAllClasses: false,     // Passed as-is (false = don't add)
             addItemTypes: false             // Passed as-is (false = don't add, must be ticked to add)
         },
         rules: {