diff --git a/source/blender/blenkernel/intern/blendfile_link_append.c b/source/blender/blenkernel/intern/blendfile_link_append.c
index 3f3c1028d10..49b480fcb64 100644
--- a/source/blender/blenkernel/intern/blendfile_link_append.c
+++ b/source/blender/blenkernel/intern/blendfile_link_append.c
@@ -574,7 +574,8 @@ static void loose_data_instantiate_obdata_preprocess(
  * (return false). */
 static bool loose_data_instantiate_collection_parents_check_recursive(Collection *collection)
 {
-  for (CollectionParent *parent_collection = collection->parents.first; parent_collection != NULL;
+  for (CollectionParent *parent_collection = collection->runtime.parents.first;
+       parent_collection != NULL;
        parent_collection = parent_collection->next) {
     if ((parent_collection->collection->id.tag & LIB_TAG_DOIT) != 0) {
       return true;
diff --git a/source/blender/blenkernel/intern/collection.c b/source/blender/blenkernel/intern/collection.c
index 53ef78525c2..1ca870bd397 100644
--- a/source/blender/blenkernel/intern/collection.c
+++ b/source/blender/blenkernel/intern/collection.c
@@ -114,12 +114,12 @@ static void collection_copy_data(Main *bmain, ID *id_dst, const ID *id_src, cons
 
   collection_dst->flag &= ~COLLECTION_HAS_OBJECT_CACHE;
   collection_dst->flag &= ~COLLECTION_HAS_OBJECT_CACHE_INSTANCED;
-  BLI_listbase_clear(&collection_dst->object_cache);
-  BLI_listbase_clear(&collection_dst->object_cache_instanced);
+  BLI_listbase_clear(&collection_dst->runtime.object_cache);
+  BLI_listbase_clear(&collection_dst->runtime.object_cache_instanced);
 
   BLI_listbase_clear(&collection_dst->gobject);
   BLI_listbase_clear(&collection_dst->children);
-  BLI_listbase_clear(&collection_dst->parents);
+  BLI_listbase_clear(&collection_dst->runtime.parents);
 
   LISTBASE_FOREACH (CollectionChild *, child, &collection_src->children) {
     collection_child_add(collection_dst, child->collection, flag, false);
@@ -138,7 +138,7 @@ static void collection_free_data(ID *id)
 
   BLI_freelistN(&collection->gobject);
   BLI_freelistN(&collection->children);
-  BLI_freelistN(&collection->parents);
+  BLI_freelistN(&collection->runtime.parents);
 
   BKE_collection_object_cache_free(collection);
 }
@@ -148,7 +148,7 @@ static void collection_foreach_id(ID *id, LibraryForeachIDData *data)
   Collection *collection = (Collection *)id;
 
   BKE_LIB_FOREACHID_PROCESS_ID(
-      data, collection->owner_id, IDWALK_CB_LOOPBACK | IDWALK_CB_NEVER_SELF);
+      data, collection->runtime.owner_id, IDWALK_CB_LOOPBACK | IDWALK_CB_NEVER_SELF);
 
   LISTBASE_FOREACH (CollectionObject *, cob, &collection->gobject) {
     BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, cob->ob, IDWALK_CB_USER);
@@ -157,7 +157,7 @@ static void collection_foreach_id(ID *id, LibraryForeachIDData *data)
     BKE_LIB_FOREACHID_PROCESS_IDSUPER(
         data, child->collection, IDWALK_CB_NEVER_SELF | IDWALK_CB_USER);
   }
-  LISTBASE_FOREACH (CollectionParent *, parent, &collection->parents) {
+  LISTBASE_FOREACH (CollectionParent *, parent, &collection->runtime.parents) {
     /* XXX This is very weak. The whole idea of keeping pointers to private IDs is very bad
      * anyway... */
     const int cb_flag = ((parent->collection != NULL &&
@@ -178,11 +178,12 @@ static ID **collection_owner_pointer_get(ID *id)
 
   Collection *master_collection = (Collection *)id;
   BLI_assert((master_collection->flag & COLLECTION_IS_MASTER) != 0);
-  BLI_assert(master_collection->owner_id != NULL);
-  BLI_assert(GS(master_collection->owner_id->name) == ID_SCE);
-  BLI_assert(((Scene *)master_collection->owner_id)->master_collection == master_collection);
+  BLI_assert(master_collection->runtime.owner_id != NULL);
+  BLI_assert(GS(master_collection->runtime.owner_id->name) == ID_SCE);
+  BLI_assert(((Scene *)master_collection->runtime.owner_id)->master_collection ==
+             master_collection);
 
-  return &master_collection->owner_id;
+  return &master_collection->runtime.owner_id;
 }
 
 void BKE_collection_blend_write_nolib(BlendWriter *writer, Collection *collection)
@@ -208,10 +209,10 @@ static void collection_blend_write(BlendWriter *writer, ID *id, const void *id_a
   /* Clean up, important in undo case to reduce false detection of changed data-blocks. */
   collection->flag &= ~COLLECTION_HAS_OBJECT_CACHE;
   collection->flag &= ~COLLECTION_HAS_OBJECT_CACHE_INSTANCED;
-  collection->tag = 0;
-  BLI_listbase_clear(&collection->object_cache);
-  BLI_listbase_clear(&collection->object_cache_instanced);
-  BLI_listbase_clear(&collection->parents);
+  collection->runtime.tag = 0;
+  BLI_listbase_clear(&collection->runtime.object_cache);
+  BLI_listbase_clear(&collection->runtime.object_cache_instanced);
+  BLI_listbase_clear(&collection->runtime.parents);
 
   /* write LibData */
   BLO_write_id_struct(writer, Collection, id_address, &collection->id);
@@ -258,7 +259,7 @@ void BKE_collection_blend_read_data(BlendDataReader *reader, Collection *collect
     }
     collection->id.flag |= LIB_EMBEDDED_DATA;
   }
-  collection->owner_id = owner_id;
+  collection->runtime.owner_id = owner_id;
 
   BLO_read_list(reader, &collection->gobject);
   BLO_read_list(reader, &collection->children);
@@ -268,10 +269,10 @@ void BKE_collection_blend_read_data(BlendDataReader *reader, Collection *collect
 
   collection->flag &= ~COLLECTION_HAS_OBJECT_CACHE;
   collection->flag &= ~COLLECTION_HAS_OBJECT_CACHE_INSTANCED;
-  collection->tag = 0;
-  BLI_listbase_clear(&collection->object_cache);
-  BLI_listbase_clear(&collection->object_cache_instanced);
-  BLI_listbase_clear(&collection->parents);
+  collection->runtime.tag = 0;
+  BLI_listbase_clear(&collection->runtime.object_cache);
+  BLI_listbase_clear(&collection->runtime.object_cache_instanced);
+  BLI_listbase_clear(&collection->runtime.parents);
 
 #ifdef USE_COLLECTION_COMPAT_28
   /* This runs before the very first doversion. */
@@ -543,7 +544,7 @@ bool BKE_collection_delete(Main *bmain, Collection *collection, bool hierarchy)
   else {
     /* Link child collections into parent collection. */
     LISTBASE_FOREACH (CollectionChild *, child, &collection->children) {
-      LISTBASE_FOREACH (CollectionParent *, cparent, &collection->parents) {
+      LISTBASE_FOREACH (CollectionParent *, cparent, &collection->runtime.parents) {
         Collection *parent = cparent->collection;
         collection_child_add(parent, child->collection, 0, true);
       }
@@ -552,7 +553,7 @@ bool BKE_collection_delete(Main *bmain, Collection *collection, bool hierarchy)
     CollectionObject *cob = collection->gobject.first;
     while (cob != NULL) {
       /* Link child object into parent collections. */
-      LISTBASE_FOREACH (CollectionParent *, cparent, &collection->parents) {
+      LISTBASE_FOREACH (CollectionParent *, cparent, &collection->runtime.parents) {
         Collection *parent = cparent->collection;
         collection_object_add(bmain, parent, cob->ob, 0, true);
       }
@@ -816,13 +817,13 @@ ListBase BKE_collection_object_cache_get(Collection *collection)
 
     BLI_mutex_lock(&cache_lock);
     if (!(collection->flag & COLLECTION_HAS_OBJECT_CACHE)) {
-      collection_object_cache_fill(&collection->object_cache, collection, 0, false);
+      collection_object_cache_fill(&collection->runtime.object_cache, collection, 0, false);
       collection->flag |= COLLECTION_HAS_OBJECT_CACHE;
     }
     BLI_mutex_unlock(&cache_lock);
   }
 
-  return collection->object_cache;
+  return collection->runtime.object_cache;
 }
 
 ListBase BKE_collection_object_cache_instanced_get(Collection *collection)
@@ -832,13 +833,14 @@ ListBase BKE_collection_object_cache_instanced_get(Collection *collection)
 
     BLI_mutex_lock(&cache_lock);
     if (!(collection->flag & COLLECTION_HAS_OBJECT_CACHE_INSTANCED)) {
-      collection_object_cache_fill(&collection->object_cache_instanced, collection, 0, true);
+      collection_object_cache_fill(
+          &collection->runtime.object_cache_instanced, collection, 0, true);
       collection->flag |= COLLECTION_HAS_OBJECT_CACHE_INSTANCED;
     }
     BLI_mutex_unlock(&cache_lock);
   }
 
-  return collection->object_cache_instanced;
+  return collection->runtime.object_cache_instanced;
 }
 
 static void collection_object_cache_free(Collection *collection)
@@ -846,10 +848,10 @@ static void collection_object_cache_free(Collection *collection)
   /* Clear own cache an for all parents, since those are affected by changes as well. */
   collection->flag &= ~COLLECTION_HAS_OBJECT_CACHE;
   collection->flag &= ~COLLECTION_HAS_OBJECT_CACHE_INSTANCED;
-  BLI_freelistN(&collection->object_cache);
-  BLI_freelistN(&collection->object_cache_instanced);
+  BLI_freelistN(&collection->runtime.object_cache);
+  BLI_freelistN(&collection->runtime.object_cache_instanced);
 
-  LISTBASE_FOREACH (CollectionParent *, parent, &collection->parents) {
+  LISTBASE_FOREACH (CollectionParent *, parent, &collection->runtime.parents) {
     collection_object_cache_free(parent->collection);
   }
 }
@@ -884,7 +886,7 @@ Collection *BKE_collection_master_add(Scene *scene)
   Collection *master_collection = BKE_libblock_alloc(
       NULL, ID_GR, BKE_SCENE_COLLECTION_NAME, LIB_ID_CREATE_NO_MAIN);
   master_collection->id.flag |= LIB_EMBEDDED_DATA;
-  master_collection->owner_id = &scene->id;
+  master_collection->runtime.owner_id = &scene->id;
   master_collection->flag |= COLLECTION_IS_MASTER;
   master_collection->color_tag = COLLECTION_COLOR_NONE;
 
@@ -1024,7 +1026,7 @@ static void collection_tag_update_parent_recursive(Main *bmain,
 
   DEG_id_tag_update_ex(bmain, &collection->id, flag);
 
-  LISTBASE_FOREACH (CollectionParent *, collection_parent, &collection->parents) {
+  LISTBASE_FOREACH (CollectionParent *, collection_parent, &collection->runtime.parents) {
     if (collection_parent->collection->flag & COLLECTION_IS_MASTER) {
       /* We don't care about scene/master collection here. */
       continue;
@@ -1045,7 +1047,7 @@ static Collection *collection_parent_editable_find_recursive(const ViewLayer *vi
     return NULL;
   }
 
-  LISTBASE_FOREACH (CollectionParent *, collection_parent, &collection->parents) {
+  LISTBASE_FOREACH (CollectionParent *, collection_parent, &collection->runtime.parents) {
     if (!ID_IS_LINKED(collection_parent->collection) &&
         !ID_IS_OVERRIDE_LIBRARY(collection_parent->collection)) {
       if (view_layer != NULL &&
@@ -1344,9 +1346,9 @@ static void collection_null_children_remove(Collection *collection)
 
 static void collection_missing_parents_remove(Collection *collection)
 {
-  LISTBASE_FOREACH_MUTABLE (CollectionParent *, parent, &collection->parents) {
+  LISTBASE_FOREACH_MUTABLE (CollectionParent *, parent, &collection->runtime.parents) {
     if ((parent->collection == NULL) || !collection_find_child(parent->collection, collection)) {
-      BLI_freelinkN(&collection->parents, parent);
+      BLI_freelinkN(&collection->runtime.parents, parent);
     }
   }
 }
@@ -1380,11 +1382,11 @@ void BKE_collections_child_remove_nulls(Main *bmain,
     }
   }
   else {
-    LISTBASE_FOREACH_MUTABLE (CollectionParent *, parent, &child_collection->parents) {
+    LISTBASE_FOREACH_MUTABLE (CollectionParent *, parent, &child_collection->runtime.parents) {
       collection_null_children_remove(parent->collection);
 
       if (!collection_find_child(parent->collection, child_collection)) {
-        BLI_freelinkN(&child_collection->parents, parent);
+        BLI_freelinkN(&child_collection->runtime.parents, parent);
       }
     }
   }
@@ -1420,7 +1422,7 @@ bool BKE_collection_is_in_scene(Collection *collection)
     return true;
   }
 
-  LISTBASE_FOREACH (CollectionParent *, cparent, &collection->parents) {
+  LISTBASE_FOREACH (CollectionParent *, cparent, &collection->runtime.parents) {
     if (BKE_collection_is_in_scene(cparent->collection)) {
       return true;
     }
@@ -1474,7 +1476,7 @@ bool BKE_collection_cycle_find(Collection *new_ancestor, Collection *collection)
     collection = new_ancestor;
   }
 
-  LISTBASE_FOREACH (CollectionParent *, parent, &new_ancestor->parents) {
+  LISTBASE_FOREACH (CollectionParent *, parent, &new_ancestor->runtime.parents) {
     if (BKE_collection_cycle_find(parent->collection, collection)) {
       return true;
     }
@@ -1514,7 +1516,7 @@ static bool collection_cycle_fix_recursive(Main *bmain,
 {
   bool cycles_found = false;
 
-  LISTBASE_FOREACH_MUTABLE (CollectionParent *, parent, &parent_collection->parents) {
+  LISTBASE_FOREACH_MUTABLE (CollectionParent *, parent, &parent_collection->runtime.parents) {
     if (BKE_collection_cycle_find(parent->collection, collection)) {
       BKE_collection_child_remove(bmain, parent->collection, parent_collection);
       cycles_found = true;
@@ -1560,7 +1562,7 @@ bool BKE_collection_has_collection(const Collection *parent, const Collection *c
 
 static CollectionParent *collection_find_parent(Collection *child, Collection *collection)
 {
-  return BLI_findptr(&child->parents, collection, offsetof(CollectionParent, collection));
+  return BLI_findptr(&child->runtime.parents, collection, offsetof(CollectionParent, collection));
 }
 
 static bool collection_child_add(Collection *parent,
@@ -1584,7 +1586,7 @@ static bool collection_child_add(Collection *parent,
   if ((flag & LIB_ID_CREATE_NO_MAIN) == 0) {
     CollectionParent *cparent = MEM_callocN(sizeof(CollectionParent), "CollectionParent");
     cparent->collection = parent;
-    BLI_addtail(&collection->parents, cparent);
+    BLI_addtail(&collection->runtime.parents, cparent);
   }
 
   if (add_us) {
@@ -1604,7 +1606,7 @@ static bool collection_child_remove(Collection *parent, Collection *collection)
   }
 
   CollectionParent *cparent = collection_find_parent(collection, parent);
-  BLI_freelinkN(&collection->parents, cparent);
+  BLI_freelinkN(&collection->runtime.parents, cparent);
   BLI_freelinkN(&parent->children, child);
 
   id_us_min(&collection->id);
@@ -1664,19 +1666,19 @@ void BKE_collection_parent_relations_rebuild(Collection *collection)
     BLI_assert(collection_find_parent(child->collection, collection) == NULL);
     CollectionParent *cparent = MEM_callocN(sizeof(CollectionParent), __func__);
     cparent->collection = collection;
-    BLI_addtail(&child->collection->parents, cparent);
+    BLI_addtail(&child->collection->runtime.parents, cparent);
   }
 }
 
 static void collection_parents_rebuild_recursive(Collection *collection)
 {
   /* A same collection may be child of several others, no need to process it more than once. */
-  if ((collection->tag & COLLECTION_TAG_RELATION_REBUILD) == 0) {
+  if ((collection->runtime.tag & COLLECTION_TAG_RELATION_REBUILD) == 0) {
     return;
   }
 
   BKE_collection_parent_relations_rebuild(collection);
-  collection->tag &= ~COLLECTION_TAG_RELATION_REBUILD;
+  collection->runtime.tag &= ~COLLECTION_TAG_RELATION_REBUILD;
 
   LISTBASE_FOREACH (CollectionChild *, child, &collection->children) {
     /* See comment above in `BKE_collection_parent_relations_rebuild`. */
@@ -1691,9 +1693,9 @@ void BKE_main_collections_parent_relations_rebuild(Main *bmain)
 {
   /* Only collections not in bmain (master ones in scenes) have no parent... */
   LISTBASE_FOREACH (Collection *, collection, &bmain->collections) {
-    BLI_freelistN(&collection->parents);
+    BLI_freelistN(&collection->runtime.parents);
 
-    collection->tag |= COLLECTION_TAG_RELATION_REBUILD;
+    collection->runtime.tag |= COLLECTION_TAG_RELATION_REBUILD;
   }
 
   /* Scene's master collections will be 'root' parent of most of our collections, so start with
@@ -1702,8 +1704,8 @@ void BKE_main_collections_parent_relations_rebuild(Main *bmain)
     /* This function can be called from readfile.c, when this pointer is not guaranteed to be NULL.
      */
     if (scene->master_collection != NULL) {
-      BLI_assert(BLI_listbase_is_empty(&scene->master_collection->parents));
-      scene->master_collection->tag |= COLLECTION_TAG_RELATION_REBUILD;
+      BLI_assert(BLI_listbase_is_empty(&scene->master_collection->runtime.parents));
+      scene->master_collection->runtime.tag |= COLLECTION_TAG_RELATION_REBUILD;
       collection_parents_rebuild_recursive(scene->master_collection);
     }
   }
@@ -1711,7 +1713,7 @@ void BKE_main_collections_parent_relations_rebuild(Main *bmain)
   /* We may have parent chains outside of scene's master_collection context? At least, readfile's
    * lib_link_collection_data() seems to assume that, so do the same here. */
   LISTBASE_FOREACH (Collection *, collection, &bmain->collections) {
-    if (collection->tag & COLLECTION_TAG_RELATION_REBUILD) {
+    if (collection->runtime.tag & COLLECTION_TAG_RELATION_REBUILD) {
       /* NOTE: we do not have easy access to 'which collections is root' info in that case, which
        * means test for cycles in collection relationships may fail here. I don't think that is an
        * issue in practice here, but worth keeping in mind... */
diff --git a/source/blender/blenkernel/intern/layer.cc b/source/blender/blenkernel/intern/layer.cc
index 95c341212d1..40b80ddbd10 100644
--- a/source/blender/blenkernel/intern/layer.cc
+++ b/source/blender/blenkernel/intern/layer.cc
@@ -626,7 +626,8 @@ static bool layer_collection_hidden(ViewLayer *view_layer, LayerCollection *lc)
   }
 
   /* Restriction flags stay set, so we need to check parents */
-  CollectionParent *parent = static_cast<CollectionParent *>(lc->collection->parents.first);
+  CollectionParent *parent = static_cast<CollectionParent *>(
+      lc->collection->runtime.parents.first);
 
   if (parent) {
     lc = BKE_layer_collection_first_from_scene_collection(view_layer, parent->collection);
@@ -662,7 +663,8 @@ bool BKE_layer_collection_activate(ViewLayer *view_layer, LayerCollection *lc)
 
 LayerCollection *BKE_layer_collection_activate_parent(ViewLayer *view_layer, LayerCollection *lc)
 {
-  CollectionParent *parent = static_cast<CollectionParent *>(lc->collection->parents.first);
+  CollectionParent *parent = static_cast<CollectionParent *>(
+      lc->collection->runtime.parents.first);
 
   if (parent) {
     lc = BKE_layer_collection_first_from_scene_collection(view_layer, parent->collection);
diff --git a/source/blender/blenkernel/intern/scene.cc b/source/blender/blenkernel/intern/scene.cc
index 124de007ade..cdffbcea527 100644
--- a/source/blender/blenkernel/intern/scene.cc
+++ b/source/blender/blenkernel/intern/scene.cc
@@ -277,7 +277,7 @@ static void scene_copy_data(Main *bmain, ID *id_dst, const ID *id_src, const int
                    (ID *)scene_src->master_collection,
                    (ID **)&scene_dst->master_collection,
                    flag_private_id_data);
-    scene_dst->master_collection->owner_id = &scene_dst->id;
+    scene_dst->master_collection->runtime.owner_id = &scene_dst->id;
   }
 
   /* View Layers */
diff --git a/source/blender/editors/interface/interface_templates.cc b/source/blender/editors/interface/interface_templates.cc
index 4a0999e26df..91c8911b97d 100644
--- a/source/blender/editors/interface/interface_templates.cc
+++ b/source/blender/editors/interface/interface_templates.cc
@@ -609,7 +609,7 @@ static void template_id_liboverride_hierarchy_collection_root_find_recursive(
       *r_collection_parent_best = collection;
     }
   }
-  for (CollectionParent *iter = static_cast<CollectionParent *>(collection->parents.first);
+  for (CollectionParent *iter = static_cast<CollectionParent *>(collection->runtime.parents.first);
        iter != nullptr;
        iter = iter->next) {
     if (iter->collection->id.lib != collection->id.lib && ID_IS_LINKED(iter->collection)) {
@@ -628,7 +628,8 @@ static void template_id_liboverride_hierarchy_collections_tag_recursive(
   /* Tag all local parents of the root collection, so that usages of the root collection and other
    * linked ones can be replaced by the local overrides in those parents too. */
   if (do_parents) {
-    for (CollectionParent *iter = static_cast<CollectionParent *>(root_collection->parents.first);
+    for (CollectionParent *iter =
+             static_cast<CollectionParent *>(root_collection->runtime.parents.first);
          iter != nullptr;
          iter = iter->next) {
       if (ID_IS_LINKED(iter->collection)) {
diff --git a/source/blender/editors/object/object_relations.c b/source/blender/editors/object/object_relations.c
index 10068def991..5315e89c62d 100644
--- a/source/blender/editors/object/object_relations.c
+++ b/source/blender/editors/object/object_relations.c
@@ -2435,7 +2435,7 @@ static int make_override_library_exec(bContext *C, wmOperator *op)
         case ID_GR: {
           Collection *collection_root = (Collection *)id_root;
           LISTBASE_FOREACH_MUTABLE (
-              CollectionParent *, collection_parent, &collection_root->parents) {
+              CollectionParent *, collection_parent, &collection_root->runtime.parents) {
             if (ID_IS_LINKED(collection_parent->collection) ||
                 !BKE_view_layer_has_collection(view_layer, collection_parent->collection)) {
               continue;
diff --git a/source/blender/editors/space_outliner/outliner_collections.cc b/source/blender/editors/space_outliner/outliner_collections.cc
index 7eceb9c11b9..9a557627abb 100644
--- a/source/blender/editors/space_outliner/outliner_collections.cc
+++ b/source/blender/editors/space_outliner/outliner_collections.cc
@@ -368,7 +368,7 @@ void outliner_collection_delete(
           skip = true;
         }
         else {
-          LISTBASE_FOREACH (CollectionParent *, cparent, &collection->parents) {
+          LISTBASE_FOREACH (CollectionParent *, cparent, &collection->runtime.parents) {
             Collection *parent = cparent->collection;
             if (ID_IS_LINKED(parent) || ID_IS_OVERRIDE_LIBRARY(parent)) {
               skip = true;
diff --git a/source/blender/editors/space_outliner/outliner_dragdrop.cc b/source/blender/editors/space_outliner/outliner_dragdrop.cc
index 3b07c6da5fa..4be4233b24b 100644
--- a/source/blender/editors/space_outliner/outliner_dragdrop.cc
+++ b/source/blender/editors/space_outliner/outliner_dragdrop.cc
@@ -1235,7 +1235,7 @@ static char *collection_drop_tooltip(bContext *C,
 
     /* Test if we are moving within same parent collection. */
     bool same_level = false;
-    LISTBASE_FOREACH (CollectionParent *, parent, &data.to->parents) {
+    LISTBASE_FOREACH (CollectionParent *, parent, &data.to->runtime.parents) {
       if (data.from == parent->collection) {
         same_level = true;
       }
diff --git a/source/blender/editors/space_outliner/outliner_draw.cc b/source/blender/editors/space_outliner/outliner_draw.cc
index df96d530abf..7b9f830a248 100644
--- a/source/blender/editors/space_outliner/outliner_draw.cc
+++ b/source/blender/editors/space_outliner/outliner_draw.cc
@@ -560,7 +560,7 @@ void outliner_collection_isolate_flag(Scene *scene,
   else {
     CollectionParent *parent;
     Collection *child = collection;
-    while ((parent = static_cast<CollectionParent *>(child->parents.first))) {
+    while ((parent = static_cast<CollectionParent *>(child->runtime.parents.first))) {
       if (parent->collection->flag & COLLECTION_IS_MASTER) {
         break;
       }
diff --git a/source/blender/editors/space_outliner/tree/tree_display_libraries.cc b/source/blender/editors/space_outliner/tree/tree_display_libraries.cc
index 405f1dd73f4..16258899f2e 100644
--- a/source/blender/editors/space_outliner/tree/tree_display_libraries.cc
+++ b/source/blender/editors/space_outliner/tree/tree_display_libraries.cc
@@ -189,7 +189,7 @@ bool TreeDisplayLibraries::library_id_filter_poll(const Library *lib, ID *id) co
     Collection *collection = (Collection *)id;
     bool has_non_scene_parent = false;
 
-    for (CollectionParent *cparent : List<CollectionParent>(collection->parents)) {
+    for (CollectionParent *cparent : List<CollectionParent>(collection->runtime.parents)) {
       if (!(cparent->collection->flag & COLLECTION_IS_MASTER)) {
         has_non_scene_parent = true;
       }
diff --git a/source/blender/makesdna/DNA_collection_types.h b/source/blender/makesdna/DNA_collection_types.h
index 75bfc2575a5..d97d3d17182 100644
--- a/source/blender/makesdna/DNA_collection_types.h
+++ b/source/blender/makesdna/DNA_collection_types.h
@@ -44,12 +44,31 @@ enum eCollectionLineArt_Flags {
   COLLECTION_LRT_USE_INTERSECTION_PRIORITY = (1 << 1),
 };
 
+typedef struct Collection_Runtime {
+  /** The ID owning this collection, in case it is an embedded one. */
+  ID *owner_id;
+
+  /**
+   * Cache of objects in this collection and all its children.
+   * This is created on demand when e.g. some physics simulation needs it,
+   * we don't want to have it for every collections due to memory usage reasons.
+   */
+  ListBase object_cache;
+
+  /** Need this for line art sub-collection selections. */
+  ListBase object_cache_instanced;
+
+  /** List of collections that are a parent of this data-block. */
+  ListBase parents;
+
+  uint8_t tag;
+
+  char _pad0[7];
+} Collection_Runtime;
+
 typedef struct Collection {
   ID id;
 
-  /** The ID owning this node tree, in case it is an embedded one. */
-  ID *owner_id;
-
   /** CollectionObject. */
   ListBase gobject;
   /** CollectionChild. */
@@ -60,56 +79,51 @@ typedef struct Collection {
   unsigned int layer DNA_DEPRECATED;
   float instance_offset[3];
 
-  short flag;
-  /* Runtime-only, always cleared on file load. */
-  short tag;
+  uint8_t flag;
+  int8_t color_tag;
 
-  short lineart_usage;         /* eCollectionLineArt_Usage */
-  unsigned char lineart_flags; /* eCollectionLineArt_Flags */
-  unsigned char lineart_intersection_mask;
-  unsigned char lineart_intersection_priority;
-  char _pad[5];
+  char _pad0[2];
 
-  int16_t color_tag;
+  uint8_t lineart_usage; /* #eCollectionLineArt_Usage */
+  uint8_t lineart_flags; /* #eCollectionLineArt_Flags */
+  uint8_t lineart_intersection_mask;
+  uint8_t lineart_intersection_priority;
 
-  /* Runtime. Cache of objects in this collection and all its
-   * children. This is created on demand when e.g. some physics
-   * simulation needs it, we don't want to have it for every
-   * collections due to memory usage reasons. */
-  ListBase object_cache;
-
-  /* Need this for line art sub-collection selections. */
-  ListBase object_cache_instanced;
-
-  /* Runtime. List of collections that are a parent of this
-   * datablock. */
-  ListBase parents;
-
-  /* Deprecated */
   struct SceneCollection *collection DNA_DEPRECATED;
   struct ViewLayer *view_layer DNA_DEPRECATED;
+
+  /* Keep last. */
+  Collection_Runtime runtime;
 } Collection;
 
-/* Collection->flag */
+/** #Collection.flag */
 enum {
-  COLLECTION_HIDE_VIEWPORT = (1 << 0),             /* Disable in viewports. */
-  COLLECTION_HIDE_SELECT = (1 << 1),               /* Not selectable in viewport. */
-  /* COLLECTION_DISABLED_DEPRECATED = (1 << 2), */ /* Not used anymore */
-  COLLECTION_HIDE_RENDER = (1 << 3),               /* Disable in renders. */
-  COLLECTION_HAS_OBJECT_CACHE = (1 << 4),          /* Runtime: object_cache is populated. */
-  COLLECTION_IS_MASTER = (1 << 5), /* Is master collection embedded in the scene. */
-  COLLECTION_HAS_OBJECT_CACHE_INSTANCED = (1 << 6), /* for object_cache_instanced. */
+  /** Disable in viewports. */
+  COLLECTION_HIDE_VIEWPORT = (1 << 0),
+  /** Not selectable in viewport. */
+  COLLECTION_HIDE_SELECT = (1 << 1),
+  // COLLECTION_DISABLED_DEPRECATED = (1 << 2), /* DIRTY */
+  /** Disable in renders. */
+  COLLECTION_HIDE_RENDER = (1 << 3),
+  /** Runtime: object_cache is populated. */
+  COLLECTION_HAS_OBJECT_CACHE = (1 << 4),
+  /** Is master collection embedded in the scene. */
+  COLLECTION_IS_MASTER = (1 << 5),
+  /** for object_cache_instanced. */
+  COLLECTION_HAS_OBJECT_CACHE_INSTANCED = (1 << 6),
 };
 
-/* Collection->tag */
+/** #Collection_Runtime.tag */
 enum {
-  /* That code (BKE_main_collections_parent_relations_rebuild and the like)
+  /**
+   * That code (#BKE_main_collections_parent_relations_rebuild and the like)
    * is called from very low-level places, like e.g ID remapping...
-   * Using a generic tag like LIB_TAG_DOIT for this is just impossible, we need our very own. */
+   * Using a generic tag like #LIB_TAG_DOIT for this is just impossible, we need our very own.
+   */
   COLLECTION_TAG_RELATION_REBUILD = (1 << 0),
 };
 
-/* Collection->color_tag. */
+/** #Collection.color_tag */
 typedef enum CollectionColorTag {
   COLLECTION_COLOR_NONE = -1,
   COLLECTION_COLOR_01,
diff --git a/source/blender/makesrna/intern/rna_collection.c b/source/blender/makesrna/intern/rna_collection.c
index 833495dce7a..4fbefb68d6b 100644
--- a/source/blender/makesrna/intern/rna_collection.c
+++ b/source/blender/makesrna/intern/rna_collection.c
@@ -31,6 +31,9 @@ const EnumPropertyItem rna_enum_collection_color_items[] = {
     {COLLECTION_COLOR_08, "COLOR_08", ICON_COLLECTION_COLOR_08, "Color 08", ""},
     {0, NULL, 0, NULL, NULL},
 };
+/* Minus 1 for NONE & 1 for the NULL sentinel. */
+BLI_STATIC_ASSERT(ARRAY_SIZE(rna_enum_collection_color_items) - 2 == COLLECTION_COLOR_TOT,
+                  "Collection color total is an invalid size");
 
 #ifdef RNA_RUNTIME