abstraction/.ssp: fix doc structure representation

fix to --abstraction/.ssp: fix document structure, representation
parent, ancestors, children. Make parent_ocn, the marked-up and
collapsed ancestor arrays, and the children correctly represent
the document structure. fixed

(assisted by Claude-Code)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01836BxBb8LvVKJ8sBg7Dx6U

9 files changed, 325 insertions, 111 deletions

diff --git a/org/ocda.org b/org/ocda.org
index 3a287e8..25a5d8e 100644
--- a/org/ocda.org
+++ b/org/ocda.org
@@ -1039,16 +1039,11 @@ ST_endnotes en_st = note_section.backmatter_endnote_objects(obj_cite_digits, opt
   the_document_head_section ~= the_document_body_section[0];
   the_document_body_section = the_document_body_section[1..$];
 }
-{ // document ancestors
-  ST_ancestors get_ancestors;
-  get_ancestors = the_document_body_section.after_doc_determine_ancestors(the_document_endnotes_section, the_document_glossary_section, the_document_bibliography_section, the_document_bookindex_section, the_document_blurb_section);
-  the_document_body_section         = get_ancestors.the_document_body_section;
-  the_document_endnotes_section     = get_ancestors.the_document_endnotes_section;
-  the_document_glossary_section     = get_ancestors.the_document_glossary_section;
-  the_document_bibliography_section = get_ancestors.the_document_bibliography_section;
-  the_document_bookindex_section    = get_ancestors.the_document_bookindex_section;
-  the_document_blurb_section        = get_ancestors.the_document_blurb_section;
-}
+/+ ↓ document ancestors: moved to run after every sections ocn have been
+     generated (the backmatter section headings are given their ocn in the
+     per section loops below) and ahead of descendants & children which
+     depend on parent_ocn
++/
 { // document segnames
   ST_segnames get_segnames;
   get_segnames = the_document_body_section.after_doc_determine_segnames(the_document_endnotes_section, the_document_glossary_section, the_document_bibliography_section, the_document_bookindex_section, the_document_blurb_section, segnames, html_segnames_ptr_cntr, html_segnames_ptr);
@@ -1338,6 +1333,25 @@ if (the_document_blurb_section.length > 1) { // writeln("blurb");
     obj = _links(obj);
   }
 }
+{ // document ancestors
+  ST_ancestors get_ancestors;
+  get_ancestors =
+    the_document_body_section.after_doc_determine_ancestors(
+      the_document_endnotes_section,
+      the_document_glossary_section,
+      the_document_bibliography_section,
+      the_document_bookindex_section,
+      the_document_blurb_section,
+      the_document_head_section
+    );
+  the_document_body_section         = get_ancestors.the_document_body_section;
+  the_document_head_section         = get_ancestors.the_document_head_section;
+  the_document_endnotes_section     = get_ancestors.the_document_endnotes_section;
+  the_document_glossary_section     = get_ancestors.the_document_glossary_section;
+  the_document_bibliography_section = get_ancestors.the_document_bibliography_section;
+  the_document_bookindex_section    = get_ancestors.the_document_bookindex_section;
+  the_document_blurb_section        = get_ancestors.the_document_blurb_section;
+}
 // get descendants
 if (the_document_body_section.length > 1) {
   auto pairs = after_doc_get_descendants(
@@ -1449,19 +1463,43 @@ if (the_document_body_section.length > 1) {
 /+ ↓ compute children_headings for heading objects +/
 {
   int[][int] heading_children;
-  foreach (obj; the_document_body_section) {
-    if (obj.metainfo.is_a == "heading" && obj.metainfo.parent_ocn != 0) {
-      heading_children[obj.metainfo.parent_ocn] ~= obj.metainfo.ocn;
-    }
-  }
-  foreach (ref obj; the_document_head_section) {
-    if (obj.metainfo.is_a == "heading" && obj.metainfo.ocn in heading_children) {
-      obj.metainfo.children_headings = heading_children[obj.metainfo.ocn];
+  /+ ↓ substantive headings only (ocn 0 is an author suppressed heading and
+       is not citable, it does not have a place in the citation structure),
+       gathered across every section not the body alone
+  +/
+  foreach (section; [
+    the_document_head_section,
+    the_document_body_section,
+    the_document_endnotes_section,
+    the_document_glossary_section,
+    the_document_bibliography_section,
+    the_document_bookindex_section,
+    the_document_blurb_section,
+  ]) {
+    foreach (obj; section) {
+      if (obj.metainfo.is_a == "heading"
+        && obj.metainfo.ocn != 0
+        && obj.metainfo.parent_ocn != 0
+        && obj.metainfo.parent_ocn != obj.metainfo.ocn
+      ) {
+        heading_children[obj.metainfo.parent_ocn] ~= obj.metainfo.ocn;
+      }
     }
   }
-  foreach (ref obj; the_document_body_section) {
-    if (obj.metainfo.is_a == "heading" && obj.metainfo.ocn in heading_children) {
-      obj.metainfo.children_headings = heading_children[obj.metainfo.ocn];
+  /+ ↓ slice copies, the elements written to are the same elements +/
+  foreach (section; [
+    the_document_head_section,
+    the_document_body_section,
+    the_document_endnotes_section,
+    the_document_glossary_section,
+    the_document_bibliography_section,
+    the_document_bookindex_section,
+    the_document_blurb_section,
+  ]) {
+    foreach (ref obj; section) {
+      if (obj.metainfo.is_a == "heading" && obj.metainfo.ocn in heading_children) {
+        obj.metainfo.children_headings = heading_children[obj.metainfo.ocn];
+      }
     }
   }
   // if (opt_action.vox_gt_2) {
diff --git a/org/ocda_functions.org b/org/ocda_functions.org
index bda15b7..21a6105 100644
--- a/org/ocda_functions.org
+++ b/org/ocda_functions.org
@@ -4580,9 +4580,6 @@ ST_the_section build_the_blurb_section(Opt) (
       }
     }
     foreach (ref obj; the_document_endnotes_section) {
-      if (obj.metainfo.is_a == "heading") {
-        obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
-      }
       if (obj.metainfo.heading_lev_markup == 4) {
         obj.ptr.html_segnames = html_segnames_ptr;
         break;
@@ -4595,9 +4592,6 @@ ST_the_section build_the_blurb_section(Opt) (
     segnames["epub"] ~= "glossary";
     html_segnames_ptr = html_segnames_ptr_cntr;
     foreach (ref obj; the_document_glossary_section) {
-      if (obj.metainfo.is_a == "heading") {
-        obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
-      }
       if (obj.metainfo.heading_lev_markup == 4) {
         obj.ptr.html_segnames = html_segnames_ptr;
         break;
@@ -4610,9 +4604,6 @@ ST_the_section build_the_blurb_section(Opt) (
     segnames["epub"] ~= "bibliography";
     html_segnames_ptr = html_segnames_ptr_cntr;
     foreach (ref obj; the_document_bibliography_section) {
-      if (obj.metainfo.is_a == "heading") {
-        obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
-      }
       if (obj.metainfo.heading_lev_markup == 4) {
         obj.ptr.html_segnames = html_segnames_ptr;
         break;
@@ -4625,9 +4616,6 @@ ST_the_section build_the_blurb_section(Opt) (
     segnames["epub"] ~= "bookindex";
     html_segnames_ptr = html_segnames_ptr_cntr;
     foreach (ref obj; the_document_bookindex_section) {
-      if (obj.metainfo.is_a == "heading") {
-        obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
-      }
       if (obj.metainfo.heading_lev_markup == 4) {
         obj.ptr.html_segnames = html_segnames_ptr;
         break;
@@ -4640,9 +4628,6 @@ ST_the_section build_the_blurb_section(Opt) (
     segnames["epub"] ~= "blurb";
     html_segnames_ptr = html_segnames_ptr_cntr;
     foreach (ref obj; the_document_blurb_section) {
-      if (obj.metainfo.is_a == "heading") {
-        obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
-      }
       if (obj.metainfo.heading_lev_markup == 4) {
         obj.ptr.html_segnames = html_segnames_ptr;
         break;
@@ -4757,10 +4742,19 @@ struct NodeStructureMetadata {
         //   "\n" ~ _text);
       }
     }
+    /+ ↓ ensure obj_cite_digit is assigned, else default 0 kept for every
+         lv0..lv7 (and every parent ocn derived from them, for headings here
+         and for non-heading objects in node_location_emitter)
+    +/
+    obj_cite_digit = obj_cite_digits.object_number;
     switch (lev_markup_number.to!int) {
     case 0:
       lv = DocStructMarkupHeading.h_sect_A;
-      lv0 = obj_cite_digit;
+      /+ ↓ document root ocn is 1 by definition; the ocn is force-set to 1
+           later (see metadoc_from_src.d head section) so guard against a
+           root emitted here with ocn 0
+      +/
+      lv0 = (obj_cite_digit > eN.bi.off) ? obj_cite_digit : 1;
       lv1 = 0; lv2 = 0; lv3 = 0; lv4 = 0; lv5 = 0; lv6 = 0; lv7 = 0;
       p_["lev_markup_number"] = 0;
       p_["object_number"] = 0;
@@ -4823,6 +4817,10 @@ struct NodeStructureMetadata {
       lv = DocStructMarkupHeading.h_text_3;
       lv6 = obj_cite_digit;
       lv7 = 0;
+      /+ ↓ markup levels are not skipped, a 3~ is enclosed by a 2~
+           (see assertions_doc_structure), the parent is that 2~,
+           lv5, whether or not its ocn is author suppressed (0)
+      +/
       p_["lev_markup_number"]
         = DocStructMarkupHeading.h_text_2;
       p_["object_number"] = lv5;
@@ -4918,6 +4916,7 @@ struct NodeStructureMetadata {
   ObjGenericComposite[] the_document_bibliography_section,
   ObjGenericComposite[] the_document_bookindex_section,
   ObjGenericComposite[] the_document_blurb_section,
+  ObjGenericComposite[] the_document_head_section,
 ) {
   int[] _get_ancestors_markup(ObjGenericComposite obj, int[] _ancestors_markup) {
     if (obj.metainfo.is_a == "heading") {
@@ -5084,30 +5083,95 @@ struct NodeStructureMetadata {
     debug(ancestor_collapsed) { writeln("collapsed: ", _ancestors_collapsed); }
     return _ancestors_collapsed;
   }
-  // multiple 1~ levels, loop through document body
-  if (the_document_body_section.length > 1) {
-    int[] _ancestors_markup = [0,0,0,0,0,0,0,0];
-    int[][] _ancestors_markup_;
-    _ancestors_markup = [1,0,0,0,0,0,0,0];
-    _ancestors_markup_ ~= _ancestors_markup;
-    int[] _ancestors_collapsed = [0,0,0,0,0,0,0,0];
-    int[][] _ancestors_collapsed_;
-    _ancestors_collapsed = [1,0,0,0,0,0,0,0];
-    _ancestors_collapsed_ ~= _ancestors_collapsed;
-    foreach (ref obj; the_document_body_section) {
-      if (obj.metainfo.is_a == "heading") {
-        obj.metainfo.markedup_ancestors = _get_ancestors_markup(obj, _ancestors_markup);
-        obj.metainfo.collapsed_ancestors = _get_ancestors_collapsed(obj, _ancestors_collapsed);
-        obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
+  /+ ↓ running ancestry state, carried across every object of the document
+       in document order. _levels_open_ records which heading levels are
+       currently open, kept separate from the ancestor ocn arrays because a
+       non-substantive (author suppressed, ocn 0) heading opens a level
+       while contributing an ocn of 0 to that slot
+  +/
+  int[] _ancestors_markup     = [1,0,0,0,0,0,0,0];
+  int[] _ancestors_collapsed  = [1,0,0,0,0,0,0,0];
+  bool[] _levels_open_markup    = [true,false,false,false,false,false,false,false];
+  bool[] _levels_open_collapsed = [true,false,false,false,false,false,false,false];
+  void _set_ancestry(ref ObjGenericComposite obj) {
+    if (obj.metainfo.is_a == "heading"
+      && obj.metainfo.heading_lev_markup  <= 7
+      && obj.metainfo.heading_lev_collapsed <= 7
+    ) {
+      /+ ↓ accumulate: the returned array must be fed back in, the helpers
+           rebind their parameter and so cannot update the caller in place
+      +/
+      _ancestors_markup    = _get_ancestors_markup(obj, _ancestors_markup);
+      _ancestors_collapsed = _get_ancestors_collapsed(obj, _ancestors_collapsed);
+      if (obj.metainfo.heading_lev_markup == 0) {
+        /+ ↓ document root ocn is 1 by definition, it is normalised to 1
+             later (head section, metadoc_from_src.d) so do not let a root
+             emitted with ocn 0 zero the root slot for the whole document
+        +/
+        _ancestors_markup[0]    = (obj.metainfo.ocn > 0) ? obj.metainfo.ocn : 1;
+        _ancestors_collapsed[0] = _ancestors_markup[0];
       }
+      foreach (_i; 0 .. 8) {
+        _levels_open_markup[_i]
+          = (_i <  obj.metainfo.heading_lev_markup)    ? _levels_open_markup[_i]
+          : (_i == obj.metainfo.heading_lev_markup)    ? true : false;
+        _levels_open_collapsed[_i]
+          = (_i <  obj.metainfo.heading_lev_collapsed) ? _levels_open_collapsed[_i]
+          : (_i == obj.metainfo.heading_lev_collapsed) ? true : false;
+      }
+    }
+    /+ ↓ every object (heading or not) carries the ancestry it sits within,
+         .dup: the helpers may return the running array itself
+    +/
+    obj.metainfo.markedup_ancestors  = _ancestors_markup.dup;
+    obj.metainfo.collapsed_ancestors = _ancestors_collapsed.dup;
+    /+ ↓ parent: nearest enclosing open heading level, for a heading that is
+         the nearest level shallower than its own
+    +/
+    int _parent_lev = 0;
+    int _depth_limit = (obj.metainfo.is_a == "heading" && obj.metainfo.heading_lev_markup <= 7)
+      ? obj.metainfo.heading_lev_markup - 1 : 7;
+    foreach_reverse (_i; 0 .. (_depth_limit + 1)) {
+      if (_levels_open_markup[_i]) {
+        _parent_lev = _i;
+        break;
+      }
+    }
+    if (!(obj.metainfo.is_a == "heading" && obj.metainfo.heading_lev_markup == 0)) {
+      obj.metainfo.parent_lev_markup = _parent_lev;
+      obj.metainfo.parent_ocn        = _ancestors_markup[_parent_lev];
     }
-    debug(ancestors) {
-      writeln("ancestors markup o_n:    ", obj.metainfo.markedup_ancestors);
-      writeln("ancestors collapsed o_n: ", obj.metainfo.markedup_ancestors);
+  }
+  /+ ↓ document order: the root (:A~) heading has been moved to the head
+       section ahead of this pass, it seeds the ancestry for everything
+  +/
+  foreach (ref obj; the_document_head_section)          { _set_ancestry(obj); }
+  foreach (ref obj; the_document_body_section)          { _set_ancestry(obj); }
+  /+ ↓ endnote objects: the ancestry given here is the heading ancestry of
+       the endnotes section itself, but an endnote's parent is the object
+       the note is called from, not a heading - that parent_ocn is set in
+       after_doc_determine_segnames, which runs ahead of this, keep it
+  +/
+  foreach (ref obj; the_document_endnotes_section)      {
+    int _parent_of_note = (obj.metainfo.is_a != "heading") ? obj.metainfo.parent_ocn : 0;
+    _set_ancestry(obj);
+    if (_parent_of_note != 0) { obj.metainfo.parent_ocn = _parent_of_note; }
+  }
+  foreach (ref obj; the_document_glossary_section)      { _set_ancestry(obj); }
+  foreach (ref obj; the_document_bibliography_section)  { _set_ancestry(obj); }
+  foreach (ref obj; the_document_bookindex_section)     { _set_ancestry(obj); }
+  foreach (ref obj; the_document_blurb_section)         { _set_ancestry(obj); }
+  debug(ancestors) {
+    foreach (obj; the_document_body_section) {
+      writeln("ocn: ", obj.metainfo.ocn,
+        " parent: ", obj.metainfo.parent_ocn,
+        " ancestors markup o_n:    ", obj.metainfo.markedup_ancestors,
+        " ancestors collapsed o_n: ", obj.metainfo.collapsed_ancestors);
     }
   }
   ST_ancestors ret;
   ret.the_document_body_section         = the_document_body_section;
+  ret.the_document_head_section         = the_document_head_section;
   ret.the_document_endnotes_section     = the_document_endnotes_section;
   ret.the_document_glossary_section     = the_document_glossary_section;
   ret.the_document_bibliography_section = the_document_bibliography_section;
diff --git a/org/ocda_obj_setter.org b/org/ocda_obj_setter.org
index 9cc9598..60d138e 100644
--- a/org/ocda_obj_setter.org
+++ b/org/ocda_obj_setter.org
@@ -248,6 +248,7 @@ struct ST_biblio_section {
 }
 struct ST_ancestors {
   ObjGenericComposite[] the_document_body_section;
+  ObjGenericComposite[] the_document_head_section;
   ObjGenericComposite[] the_document_endnotes_section;
   ObjGenericComposite[] the_document_glossary_section;
   ObjGenericComposite[] the_document_bibliography_section;
diff --git a/org/out_metadata.org b/org/out_metadata.org
index dcd7c51..8606c69 100644
--- a/org/out_metadata.org
+++ b/org/out_metadata.org
@@ -176,6 +176,10 @@ if (doc_matters.opt.action.html_link_markup_source) {
     ~ "&nbsp;🫛&nbsp;zipped&nbsp;</a>|&nbsp;"
     ~ "<a href=\"../../" ~ pth_pod.internal_base ~ "/" ~ doc_matters.src.filename_base ~ "/\" class=\"lnkicon\">"
     ~ "&nbsp;🫛&nbsp;tree&nbsp;</a>]&nbsp;";
+  /+ .ssp peg parsable source, interesting (path may be of interest for downloading) but renders poorly visually in browser +/
+  // metadata_ ~= "<p class=\"lev1\">●&nbsp;&nbsp;.ssp [peg parsable source]:"
+  //   ~              "<a href=\"../../" ~ pth_pod.internal_base ~ "/" ~ doc_matters.src.filename_base ~ "/media/abstraction/" ~  doc_matters.src.filename_base ~ "." ~ doc_matters.src.language ~ ".ssp\" class=\"lnkicon\">"
+  //   ~ "&nbsp;🗎&nbsp;.ssp [peg parsable source]&nbsp;</a>]</p>";
   metadata_ ~= "<p class=\"lev1\">●&nbsp;&nbsp;source digests:"
     ~ "&nbsp;[&nbsp;<a href=\"../../" ~ pth_pod.internal_base ~ "/" ~ doc_matters.src.filename_base ~ ".digests.txt\" class=\"lnkizipcon\">"
     ~ "&nbsp;#&nbsp;digests&nbsp;</a>]</p>";
diff --git a/org/out_xmls.org b/org/out_xmls.org
index 353ad31..52ab735 100644
--- a/org/out_xmls.org
+++ b/org/out_xmls.org
@@ -421,7 +421,7 @@ string inline_search_form(M)(
 
 ***** html head & head banner
 
-▣ ▤ ⁜ ☀ ፨ ፠ ※ ■ □ ▢ ▣ ▤ ▥ ▦ ▧ ▨ 〓 ⚏ ⚏ ⌘ 🫛 ⌥ ⟰
+▣ ▤ ⁜ ☀ ፨ ፠ ※ ■ □ ▢ ▣ ▤ ▥ ▦ ▧ ▨ 〓 ⚏ ⚏ ⌘ 🫛 🗎 ⌥ ⟰
 
 #+NAME: xhtml_format_objects_html_head
 #+BEGIN_SRC d
diff --git a/src/sisudoc/ocda/meta/metadoc_from_src.d b/src/sisudoc/ocda/meta/metadoc_from_src.d
index 7fcf3bb..dec00c6 100644
--- a/src/sisudoc/ocda/meta/metadoc_from_src.d
+++ b/src/sisudoc/ocda/meta/metadoc_from_src.d
@@ -933,16 +933,11 @@ template docAbstraction() {
       the_document_head_section ~= the_document_body_section[0];
       the_document_body_section = the_document_body_section[1..$];
     }
-    { // document ancestors
-      ST_ancestors get_ancestors;
-      get_ancestors = the_document_body_section.after_doc_determine_ancestors(the_document_endnotes_section, the_document_glossary_section, the_document_bibliography_section, the_document_bookindex_section, the_document_blurb_section);
-      the_document_body_section         = get_ancestors.the_document_body_section;
-      the_document_endnotes_section     = get_ancestors.the_document_endnotes_section;
-      the_document_glossary_section     = get_ancestors.the_document_glossary_section;
-      the_document_bibliography_section = get_ancestors.the_document_bibliography_section;
-      the_document_bookindex_section    = get_ancestors.the_document_bookindex_section;
-      the_document_blurb_section        = get_ancestors.the_document_blurb_section;
-    }
+    /+ ↓ document ancestors: moved to run after every sections ocn have been
+         generated (the backmatter section headings are given their ocn in the
+         per section loops below) and ahead of descendants & children which
+         depend on parent_ocn
+    +/
     { // document segnames
       ST_segnames get_segnames;
       get_segnames = the_document_body_section.after_doc_determine_segnames(the_document_endnotes_section, the_document_glossary_section, the_document_bibliography_section, the_document_bookindex_section, the_document_blurb_section, segnames, html_segnames_ptr_cntr, html_segnames_ptr);
@@ -1232,6 +1227,25 @@ template docAbstraction() {
         obj = _links(obj);
       }
     }
+    { // document ancestors
+      ST_ancestors get_ancestors;
+      get_ancestors =
+        the_document_body_section.after_doc_determine_ancestors(
+          the_document_endnotes_section,
+          the_document_glossary_section,
+          the_document_bibliography_section,
+          the_document_bookindex_section,
+          the_document_blurb_section,
+          the_document_head_section
+        );
+      the_document_body_section         = get_ancestors.the_document_body_section;
+      the_document_head_section         = get_ancestors.the_document_head_section;
+      the_document_endnotes_section     = get_ancestors.the_document_endnotes_section;
+      the_document_glossary_section     = get_ancestors.the_document_glossary_section;
+      the_document_bibliography_section = get_ancestors.the_document_bibliography_section;
+      the_document_bookindex_section    = get_ancestors.the_document_bookindex_section;
+      the_document_blurb_section        = get_ancestors.the_document_blurb_section;
+    }
     // get descendants
     if (the_document_body_section.length > 1) {
       auto pairs = after_doc_get_descendants(
@@ -1343,19 +1357,43 @@ template docAbstraction() {
     /+ ↓ compute children_headings for heading objects +/
     {
       int[][int] heading_children;
-      foreach (obj; the_document_body_section) {
-        if (obj.metainfo.is_a == "heading" && obj.metainfo.parent_ocn != 0) {
-          heading_children[obj.metainfo.parent_ocn] ~= obj.metainfo.ocn;
-        }
-      }
-      foreach (ref obj; the_document_head_section) {
-        if (obj.metainfo.is_a == "heading" && obj.metainfo.ocn in heading_children) {
-          obj.metainfo.children_headings = heading_children[obj.metainfo.ocn];
+      /+ ↓ substantive headings only (ocn 0 is an author suppressed heading and
+           is not citable, it does not have a place in the citation structure),
+           gathered across every section not the body alone
+      +/
+      foreach (section; [
+        the_document_head_section,
+        the_document_body_section,
+        the_document_endnotes_section,
+        the_document_glossary_section,
+        the_document_bibliography_section,
+        the_document_bookindex_section,
+        the_document_blurb_section,
+      ]) {
+        foreach (obj; section) {
+          if (obj.metainfo.is_a == "heading"
+            && obj.metainfo.ocn != 0
+            && obj.metainfo.parent_ocn != 0
+            && obj.metainfo.parent_ocn != obj.metainfo.ocn
+          ) {
+            heading_children[obj.metainfo.parent_ocn] ~= obj.metainfo.ocn;
+          }
         }
       }
-      foreach (ref obj; the_document_body_section) {
-        if (obj.metainfo.is_a == "heading" && obj.metainfo.ocn in heading_children) {
-          obj.metainfo.children_headings = heading_children[obj.metainfo.ocn];
+      /+ ↓ slice copies, the elements written to are the same elements +/
+      foreach (section; [
+        the_document_head_section,
+        the_document_body_section,
+        the_document_endnotes_section,
+        the_document_glossary_section,
+        the_document_bibliography_section,
+        the_document_bookindex_section,
+        the_document_blurb_section,
+      ]) {
+        foreach (ref obj; section) {
+          if (obj.metainfo.is_a == "heading" && obj.metainfo.ocn in heading_children) {
+            obj.metainfo.children_headings = heading_children[obj.metainfo.ocn];
+          }
         }
       }
       // if (opt_action.vox_gt_2) {
diff --git a/src/sisudoc/ocda/meta/metadoc_from_src_functions.d b/src/sisudoc/ocda/meta/metadoc_from_src_functions.d
index cf46fda..4d3d372 100644
--- a/src/sisudoc/ocda/meta/metadoc_from_src_functions.d
+++ b/src/sisudoc/ocda/meta/metadoc_from_src_functions.d
@@ -4359,9 +4359,6 @@ template docAbstractionFunctions() {
         }
       }
       foreach (ref obj; the_document_endnotes_section) {
-        if (obj.metainfo.is_a == "heading") {
-          obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
-        }
         if (obj.metainfo.heading_lev_markup == 4) {
           obj.ptr.html_segnames = html_segnames_ptr;
           break;
@@ -4374,9 +4371,6 @@ template docAbstractionFunctions() {
       segnames["epub"] ~= "glossary";
       html_segnames_ptr = html_segnames_ptr_cntr;
       foreach (ref obj; the_document_glossary_section) {
-        if (obj.metainfo.is_a == "heading") {
-          obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
-        }
         if (obj.metainfo.heading_lev_markup == 4) {
           obj.ptr.html_segnames = html_segnames_ptr;
           break;
@@ -4389,9 +4383,6 @@ template docAbstractionFunctions() {
       segnames["epub"] ~= "bibliography";
       html_segnames_ptr = html_segnames_ptr_cntr;
       foreach (ref obj; the_document_bibliography_section) {
-        if (obj.metainfo.is_a == "heading") {
-          obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
-        }
         if (obj.metainfo.heading_lev_markup == 4) {
           obj.ptr.html_segnames = html_segnames_ptr;
           break;
@@ -4404,9 +4395,6 @@ template docAbstractionFunctions() {
       segnames["epub"] ~= "bookindex";
       html_segnames_ptr = html_segnames_ptr_cntr;
       foreach (ref obj; the_document_bookindex_section) {
-        if (obj.metainfo.is_a == "heading") {
-          obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
-        }
         if (obj.metainfo.heading_lev_markup == 4) {
           obj.ptr.html_segnames = html_segnames_ptr;
           break;
@@ -4419,9 +4407,6 @@ template docAbstractionFunctions() {
       segnames["epub"] ~= "blurb";
       html_segnames_ptr = html_segnames_ptr_cntr;
       foreach (ref obj; the_document_blurb_section) {
-        if (obj.metainfo.is_a == "heading") {
-          obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
-        }
         if (obj.metainfo.heading_lev_markup == 4) {
           obj.ptr.html_segnames = html_segnames_ptr;
           break;
@@ -4529,10 +4514,19 @@ template docAbstractionFunctions() {
           //   "\n" ~ _text);
         }
       }
+      /+ ↓ ensure obj_cite_digit is assigned, else default 0 kept for every
+           lv0..lv7 (and every parent ocn derived from them, for headings here
+           and for non-heading objects in node_location_emitter)
+      +/
+      obj_cite_digit = obj_cite_digits.object_number;
       switch (lev_markup_number.to!int) {
       case 0:
         lv = DocStructMarkupHeading.h_sect_A;
-        lv0 = obj_cite_digit;
+        /+ ↓ document root ocn is 1 by definition; the ocn is force-set to 1
+             later (see metadoc_from_src.d head section) so guard against a
+             root emitted here with ocn 0
+        +/
+        lv0 = (obj_cite_digit > eN.bi.off) ? obj_cite_digit : 1;
         lv1 = 0; lv2 = 0; lv3 = 0; lv4 = 0; lv5 = 0; lv6 = 0; lv7 = 0;
         p_["lev_markup_number"] = 0;
         p_["object_number"] = 0;
@@ -4595,6 +4589,10 @@ template docAbstractionFunctions() {
         lv = DocStructMarkupHeading.h_text_3;
         lv6 = obj_cite_digit;
         lv7 = 0;
+        /+ ↓ markup levels are not skipped, a 3~ is enclosed by a 2~
+             (see assertions_doc_structure), the parent is that 2~,
+             lv5, whether or not its ocn is author suppressed (0)
+        +/
         p_["lev_markup_number"]
           = DocStructMarkupHeading.h_text_2;
         p_["object_number"] = lv5;
@@ -4690,6 +4688,7 @@ template docAbstractionFunctions() {
     ObjGenericComposite[] the_document_bibliography_section,
     ObjGenericComposite[] the_document_bookindex_section,
     ObjGenericComposite[] the_document_blurb_section,
+    ObjGenericComposite[] the_document_head_section,
   ) {
     int[] _get_ancestors_markup(ObjGenericComposite obj, int[] _ancestors_markup) {
       if (obj.metainfo.is_a == "heading") {
@@ -4856,30 +4855,95 @@ template docAbstractionFunctions() {
       debug(ancestor_collapsed) { writeln("collapsed: ", _ancestors_collapsed); }
       return _ancestors_collapsed;
     }
-    // multiple 1~ levels, loop through document body
-    if (the_document_body_section.length > 1) {
-      int[] _ancestors_markup = [0,0,0,0,0,0,0,0];
-      int[][] _ancestors_markup_;
-      _ancestors_markup = [1,0,0,0,0,0,0,0];
-      _ancestors_markup_ ~= _ancestors_markup;
-      int[] _ancestors_collapsed = [0,0,0,0,0,0,0,0];
-      int[][] _ancestors_collapsed_;
-      _ancestors_collapsed = [1,0,0,0,0,0,0,0];
-      _ancestors_collapsed_ ~= _ancestors_collapsed;
-      foreach (ref obj; the_document_body_section) {
-        if (obj.metainfo.is_a == "heading") {
-          obj.metainfo.markedup_ancestors = _get_ancestors_markup(obj, _ancestors_markup);
-          obj.metainfo.collapsed_ancestors = _get_ancestors_collapsed(obj, _ancestors_collapsed);
-          obj.metainfo.parent_ocn = obj.metainfo.markedup_ancestors[obj.metainfo.parent_lev_markup];
+    /+ ↓ running ancestry state, carried across every object of the document
+         in document order. _levels_open_ records which heading levels are
+         currently open, kept separate from the ancestor ocn arrays because a
+         non-substantive (author suppressed, ocn 0) heading opens a level
+         while contributing an ocn of 0 to that slot
+    +/
+    int[] _ancestors_markup     = [1,0,0,0,0,0,0,0];
+    int[] _ancestors_collapsed  = [1,0,0,0,0,0,0,0];
+    bool[] _levels_open_markup    = [true,false,false,false,false,false,false,false];
+    bool[] _levels_open_collapsed = [true,false,false,false,false,false,false,false];
+    void _set_ancestry(ref ObjGenericComposite obj) {
+      if (obj.metainfo.is_a == "heading"
+        && obj.metainfo.heading_lev_markup  <= 7
+        && obj.metainfo.heading_lev_collapsed <= 7
+      ) {
+        /+ ↓ accumulate: the returned array must be fed back in, the helpers
+             rebind their parameter and so cannot update the caller in place
+        +/
+        _ancestors_markup    = _get_ancestors_markup(obj, _ancestors_markup);
+        _ancestors_collapsed = _get_ancestors_collapsed(obj, _ancestors_collapsed);
+        if (obj.metainfo.heading_lev_markup == 0) {
+          /+ ↓ document root ocn is 1 by definition, it is normalised to 1
+               later (head section, metadoc_from_src.d) so do not let a root
+               emitted with ocn 0 zero the root slot for the whole document
+          +/
+          _ancestors_markup[0]    = (obj.metainfo.ocn > 0) ? obj.metainfo.ocn : 1;
+          _ancestors_collapsed[0] = _ancestors_markup[0];
         }
+        foreach (_i; 0 .. 8) {
+          _levels_open_markup[_i]
+            = (_i <  obj.metainfo.heading_lev_markup)    ? _levels_open_markup[_i]
+            : (_i == obj.metainfo.heading_lev_markup)    ? true : false;
+          _levels_open_collapsed[_i]
+            = (_i <  obj.metainfo.heading_lev_collapsed) ? _levels_open_collapsed[_i]
+            : (_i == obj.metainfo.heading_lev_collapsed) ? true : false;
+        }
+      }
+      /+ ↓ every object (heading or not) carries the ancestry it sits within,
+           .dup: the helpers may return the running array itself
+      +/
+      obj.metainfo.markedup_ancestors  = _ancestors_markup.dup;
+      obj.metainfo.collapsed_ancestors = _ancestors_collapsed.dup;
+      /+ ↓ parent: nearest enclosing open heading level, for a heading that is
+           the nearest level shallower than its own
+      +/
+      int _parent_lev = 0;
+      int _depth_limit = (obj.metainfo.is_a == "heading" && obj.metainfo.heading_lev_markup <= 7)
+        ? obj.metainfo.heading_lev_markup - 1 : 7;
+      foreach_reverse (_i; 0 .. (_depth_limit + 1)) {
+        if (_levels_open_markup[_i]) {
+          _parent_lev = _i;
+          break;
+        }
+      }
+      if (!(obj.metainfo.is_a == "heading" && obj.metainfo.heading_lev_markup == 0)) {
+        obj.metainfo.parent_lev_markup = _parent_lev;
+        obj.metainfo.parent_ocn        = _ancestors_markup[_parent_lev];
       }
-      debug(ancestors) {
-        writeln("ancestors markup o_n:    ", obj.metainfo.markedup_ancestors);
-        writeln("ancestors collapsed o_n: ", obj.metainfo.markedup_ancestors);
+    }
+    /+ ↓ document order: the root (:A~) heading has been moved to the head
+         section ahead of this pass, it seeds the ancestry for everything
+    +/
+    foreach (ref obj; the_document_head_section)          { _set_ancestry(obj); }
+    foreach (ref obj; the_document_body_section)          { _set_ancestry(obj); }
+    /+ ↓ endnote objects: the ancestry given here is the heading ancestry of
+         the endnotes section itself, but an endnote's parent is the object
+         the note is called from, not a heading - that parent_ocn is set in
+         after_doc_determine_segnames, which runs ahead of this, keep it
+    +/
+    foreach (ref obj; the_document_endnotes_section)      {
+      int _parent_of_note = (obj.metainfo.is_a != "heading") ? obj.metainfo.parent_ocn : 0;
+      _set_ancestry(obj);
+      if (_parent_of_note != 0) { obj.metainfo.parent_ocn = _parent_of_note; }
+    }
+    foreach (ref obj; the_document_glossary_section)      { _set_ancestry(obj); }
+    foreach (ref obj; the_document_bibliography_section)  { _set_ancestry(obj); }
+    foreach (ref obj; the_document_bookindex_section)     { _set_ancestry(obj); }
+    foreach (ref obj; the_document_blurb_section)         { _set_ancestry(obj); }
+    debug(ancestors) {
+      foreach (obj; the_document_body_section) {
+        writeln("ocn: ", obj.metainfo.ocn,
+          " parent: ", obj.metainfo.parent_ocn,
+          " ancestors markup o_n:    ", obj.metainfo.markedup_ancestors,
+          " ancestors collapsed o_n: ", obj.metainfo.collapsed_ancestors);
       }
     }
     ST_ancestors ret;
     ret.the_document_body_section         = the_document_body_section;
+    ret.the_document_head_section         = the_document_head_section;
     ret.the_document_endnotes_section     = the_document_endnotes_section;
     ret.the_document_glossary_section     = the_document_glossary_section;
     ret.the_document_bibliography_section = the_document_bibliography_section;
diff --git a/src/sisudoc/ocda/meta/metadoc_object_setter.d b/src/sisudoc/ocda/meta/metadoc_object_setter.d
index 9fcc2b9..a1f6a86 100644
--- a/src/sisudoc/ocda/meta/metadoc_object_setter.d
+++ b/src/sisudoc/ocda/meta/metadoc_object_setter.d
@@ -237,6 +237,7 @@ template ObjectSetter() {
   }
   struct ST_ancestors {
     ObjGenericComposite[] the_document_body_section;
+    ObjGenericComposite[] the_document_head_section;
     ObjGenericComposite[] the_document_endnotes_section;
     ObjGenericComposite[] the_document_glossary_section;
     ObjGenericComposite[] the_document_bibliography_section;
diff --git a/src/sisudoc/outputs/io_out/metadata.d b/src/sisudoc/outputs/io_out/metadata.d
index f951dde..ff9c72f 100644
--- a/src/sisudoc/outputs/io_out/metadata.d
+++ b/src/sisudoc/outputs/io_out/metadata.d
@@ -510,6 +510,10 @@ string theme_light_1 = format(q"┃
         ~ "&nbsp;🫛&nbsp;zipped&nbsp;</a>|&nbsp;"
         ~ "<a href=\"../../" ~ pth_pod.internal_base ~ "/" ~ doc_matters.src.filename_base ~ "/\" class=\"lnkicon\">"
         ~ "&nbsp;🫛&nbsp;tree&nbsp;</a>]&nbsp;";
+      /+ .ssp peg parsable source, interesting (path may be of interest for downloading) but renders poorly visually in browser +/
+      // metadata_ ~= "<p class=\"lev1\">●&nbsp;&nbsp;.ssp [peg parsable source]:"
+      //   ~              "<a href=\"../../" ~ pth_pod.internal_base ~ "/" ~ doc_matters.src.filename_base ~ "/media/abstraction/" ~  doc_matters.src.filename_base ~ "." ~ doc_matters.src.language ~ ".ssp\" class=\"lnkicon\">"
+      //   ~ "&nbsp;🗎&nbsp;.ssp [peg parsable source]&nbsp;</a>]</p>";
       metadata_ ~= "<p class=\"lev1\">●&nbsp;&nbsp;source digests:"
         ~ "&nbsp;[&nbsp;<a href=\"../../" ~ pth_pod.internal_base ~ "/" ~ doc_matters.src.filename_base ~ ".digests.txt\" class=\"lnkizipcon\">"
         ~ "&nbsp;#&nbsp;digests&nbsp;</a>]</p>";