.ssp document abstraction as PEG parsable text

  --show-abstraction flag to write .ssp document abstraction files

- Add a new output mode that serializes the in-memory document
  abstraction (produced by spineAbstraction) to a human-readable,
  line-oriented text format (.ssp). This captures the full object
  model after parsing and abstraction but before output generation.

- The .ssp format uses unambiguous line prefixes:
    @section { }  - section boundaries (head/toc/body/endnotes/...)
    [N] type      - object declaration with OCN
    .name: value  - object properties (only non-defaults)
    | content     - text content lines
    % comment     - comments

- New files:
    src/sisudoc/io_out/create_abstraction_txt.d
      Serializer module following the same template pattern as
      metadoc_show_summary.d. Walks doc.abstraction() section by
      section, writing metadata preamble (@meta, @make, @doc_has)
      then each object with its properties and text content.
      Output goes to {output_path}/{lang}/abstraction/{doc}.ssp

- Changes to spine.d:
    - Add "show-abstraction" to opts initialization, getopt, and
      OptActions struct
    - Add show_abstraction to abstraction(), require_processing_files(),
      and meta_processing_general() so the flag triggers full document
      processing
    - Insert call at both spineAbstraction sites (parallel and serial
      branches), gated by show_abstraction flag, following the same
      pattern as show_config/show_summary/show_make

- Tested against all 35 sample documents (including multilingual
  live-manual in 9 languages) - zero failures. Works standalone
  (--show-abstraction) or combined with other output flags
  (--show-abstraction --html --text). No effect on existing code
  paths when the flag is not used.

  Co-Authored-By: Anthropic Claude Opus 4.6 (1M context)

4 files changed, 657 insertions, 0 deletions

diff --git a/org/out_src_abstraction_peg_text.org b/org/out_src_abstraction_peg_text.org
new file mode 100644
index 0000000..597d8d4
--- /dev/null
+++ b/org/out_src_abstraction_peg_text.org
@@ -0,0 +1,314 @@
+-*- mode: org -*-
+#+TITLE:       sisudoc spine (doc_reform) output pod source abstraction peg text
+#+DESCRIPTION: documents - structuring, publishing in multiple formats & search
+#+FILETAGS:    :spine:output:source:pod:
+#+AUTHOR:      Ralph Amissah
+#+EMAIL:       [[mailto:ralph.amissah@gmail.com][ralph.amissah@gmail.com]]
+#+COPYRIGHT:   Copyright (C) 2015 (continuously updated, current 2026) Ralph Amissah
+#+LANGUAGE:    en
+#+STARTUP:     content hideblocks hidestars noindent entitiespretty
+#+PROPERTY:    header-args  :exports code
+#+PROPERTY:    header-args+ :noweb yes
+#+PROPERTY:    header-args+ :results silent
+#+PROPERTY:    header-args+ :cache no
+#+PROPERTY:    header-args+ :padline no
+#+PROPERTY:    header-args+ :mkdirp yes
+#+OPTIONS:     H:3 num:nil toc:t \n:t ::t |:t ^:nil -:t f:t *:t
+
+- [[./doc-reform.org][doc-reform.org]]  [[./][org/]]
+
+* (Object-Centric) Document Abstraction PEG text
+
+- Process markup document, create document abstraction
+
+** _module template_ :module:metadoc_from_src:
+
+rename source_abstraction_peg_txt.d
+
+#+HEADER: :tangle "../src/sisudoc/io_out/create_abstraction_txt.d"
+#+HEADER: :noweb yes
+#+BEGIN_SRC d
+<<doc_header_including_copyright_and_license>>
+module sisudoc.io_out.create_abstraction_txt;
+@safe:
+
+/+ ↓ write document abstraction as human-readable .ssp text file +/
+template spineAbstractionTxt() {
+  import std.conv : to;
+  import std.file;
+  import std.path;
+  import std.stdio;
+  import std.string;
+  import std.array;
+  import sisudoc.io_out.paths_output;
+
+  void spineAbstractionTxt(D)(D doc) {
+    auto doc_abstraction = doc.abstraction;
+    auto doc_matters     = doc.matters;
+    string[] output;
+
+    /+ ↓ header comment +/
+    output ~= "% SiSU Document Abstraction v0.1";
+    output ~= "% Source: " ~ doc_matters.src.filename;
+    output ~= "";
+
+    /+ ↓ @meta block +/
+    output ~= "@meta {";
+    auto meta = doc_matters.conf_make_meta.meta;
+    if (meta.title_main.length > 0)
+      output ~= "  title.main: " ~ meta.title_main;
+    if (meta.title_subtitle.length > 0)
+      output ~= "  title.subtitle: " ~ meta.title_subtitle;
+    if (meta.title_full.length > 0)
+      output ~= "  title.full: " ~ meta.title_full;
+    if (meta.title_language.length > 0)
+      output ~= "  title.language: " ~ meta.title_language;
+    if (meta.creator_author.length > 0)
+      output ~= "  creator.author: " ~ meta.creator_author;
+    if (meta.creator_author_surname.length > 0)
+      output ~= "  creator.author_surname: " ~ meta.creator_author_surname;
+    if (meta.creator_author_surname_fn.length > 0)
+      output ~= "  creator.author_surname_fn: " ~ meta.creator_author_surname_fn;
+    if (meta.creator_author_email.length > 0)
+      output ~= "  creator.author_email: " ~ meta.creator_author_email;
+    if (meta.creator_illustrator.length > 0)
+      output ~= "  creator.illustrator: " ~ meta.creator_illustrator;
+    if (meta.creator_translator.length > 0)
+      output ~= "  creator.translator: " ~ meta.creator_translator;
+    if (meta.date_published.length > 0)
+      output ~= "  date.published: " ~ meta.date_published;
+    if (meta.date_created.length > 0)
+      output ~= "  date.created: " ~ meta.date_created;
+    if (meta.date_issued.length > 0)
+      output ~= "  date.issued: " ~ meta.date_issued;
+    if (meta.date_available.length > 0)
+      output ~= "  date.available: " ~ meta.date_available;
+    if (meta.date_modified.length > 0)
+      output ~= "  date.modified: " ~ meta.date_modified;
+    if (meta.date_valid.length > 0)
+      output ~= "  date.valid: " ~ meta.date_valid;
+    if (meta.rights_copyright.length > 0)
+      output ~= "  rights.copyright: " ~ meta.rights_copyright;
+    if (meta.rights_license.length > 0)
+      output ~= "  rights.license: " ~ meta.rights_license;
+    if (meta.classify_topic_register.length > 0)
+      output ~= "  classify.topic_register: " ~ meta.classify_topic_register;
+    if (meta.classify_subject.length > 0)
+      output ~= "  classify.subject: " ~ meta.classify_subject;
+    if (meta.classify_keywords.length > 0)
+      output ~= "  classify.keywords: " ~ meta.classify_keywords;
+    if (meta.classify_loc.length > 0)
+      output ~= "  classify.loc: " ~ meta.classify_loc;
+    if (meta.classify_dewey.length > 0)
+      output ~= "  classify.dewey: " ~ meta.classify_dewey;
+    if (meta.identifier_isbn.length > 0)
+      output ~= "  identifier.isbn: " ~ meta.identifier_isbn;
+    if (meta.identifier_oclc.length > 0)
+      output ~= "  identifier.oclc: " ~ meta.identifier_oclc;
+    if (meta.language_document.length > 0)
+      output ~= "  language.document: " ~ meta.language_document;
+    if (meta.notes_abstract.length > 0)
+      output ~= "  notes.abstract: " ~ meta.notes_abstract;
+    if (meta.notes_description.length > 0)
+      output ~= "  notes.description: " ~ meta.notes_description;
+    if (meta.notes_summary.length > 0)
+      output ~= "  notes.summary: " ~ meta.notes_summary;
+    output ~= "}";
+    output ~= "";
+
+    /+ ↓ @make block +/
+    output ~= "@make {";
+    auto make = doc_matters.conf_make_meta.make;
+    if (make.doc_type.length > 0)
+      output ~= "  doc_type: " ~ make.doc_type;
+    if (make.auto_num_top_at_level.length > 0)
+      output ~= "  auto_num_top_at_level: " ~ make.auto_num_top_at_level;
+    output ~= "  auto_num_top_lv: " ~ make.auto_num_top_lv.to!string;
+    output ~= "  auto_num_depth: " ~ make.auto_num_depth.to!string;
+    output ~= "}";
+    output ~= "";
+
+    /+ ↓ @doc_has block +/
+    output ~= "@doc_has {";
+    output ~= "  inline_links: " ~ doc_matters.has.inline_links.to!string;
+    output ~= "  inline_notes_reg: " ~ doc_matters.has.inline_notes_reg.to!string;
+    output ~= "  inline_notes_star: " ~ doc_matters.has.inline_notes_star.to!string;
+    output ~= "  tables: " ~ doc_matters.has.tables.to!string;
+    output ~= "  codeblocks: " ~ doc_matters.has.codeblocks.to!string;
+    output ~= "  images: " ~ doc_matters.has.images.to!string;
+    output ~= "  poems: " ~ doc_matters.has.poems.to!string;
+    output ~= "  groups: " ~ doc_matters.has.groups.to!string;
+    output ~= "  blocks: " ~ doc_matters.has.blocks.to!string;
+    output ~= "  quotes: " ~ doc_matters.has.quotes.to!string;
+    output ~= "}";
+    output ~= "";
+
+    /+ ↓ document sections +/
+    string[] section_order = ["head", "toc", "body", "endnotes",
+      "glossary", "bibliography", "bookindex", "blurb"];
+
+    foreach (section; section_order) {
+      if (section !in doc_abstraction) continue;
+      auto section_objs = doc_abstraction[section];
+      if (section_objs.length == 0) continue;
+
+      output ~= "@" ~ section ~ " {";
+      output ~= "";
+
+      foreach (obj; section_objs) {
+        /+ ↓ object declaration line +/
+        string obj_decl = "[" ~ obj.metainfo.ocn.to!string ~ "] ";
+
+        if (obj.metainfo.is_a == "heading") {
+          string lev = obj.metainfo.marked_up_level;
+          obj_decl ~= "heading :" ~ lev;
+          if (obj.metainfo.identifier.length > 0) {
+            obj_decl ~= " " ~ obj.metainfo.identifier;
+          }
+        } else {
+          obj_decl ~= obj.metainfo.is_a;
+        }
+        output ~= obj_decl;
+
+        /+ ↓ properties (only non-default values) +/
+        if (obj.metainfo.is_of_part.length > 0)
+          output ~= ".part: " ~ obj.metainfo.is_of_part;
+        if (obj.metainfo.is_of_section.length > 0 && obj.metainfo.is_of_section != section)
+          output ~= ".section: " ~ obj.metainfo.is_of_section;
+        if (obj.metainfo.parent_ocn != 0)
+          output ~= ".parent: " ~ obj.metainfo.parent_ocn.to!string;
+        if (obj.metainfo.last_descendant_ocn != 0)
+          output ~= ".last_descendant: " ~ obj.metainfo.last_descendant_ocn.to!string;
+
+        /+ ↓ ancestors (only if non-zero) +/
+        bool has_ancestors = false;
+        foreach (a; obj.metainfo.markedup_ancestors) {
+          if (a != 0) { has_ancestors = true; break; }
+        }
+        if (has_ancestors) {
+          string anc;
+          foreach (i, a; obj.metainfo.markedup_ancestors) {
+            if (i > 0) anc ~= " ";
+            anc ~= a.to!string;
+          }
+          output ~= ".ancestors: " ~ anc;
+        }
+
+        if (obj.metainfo.dummy_heading)
+          output ~= ".dummy: true";
+        if (obj.metainfo.object_number_off)
+          output ~= ".ocn_off: true";
+
+        /+ ↓ text attributes +/
+        if (obj.attrib.indent_base != 0 || obj.attrib.indent_hang != 0)
+          output ~= ".indent: " ~ obj.attrib.indent_base.to!string
+            ~ " " ~ obj.attrib.indent_hang.to!string;
+        if (obj.attrib.bullet)
+          output ~= ".bullet: true";
+        if (obj.attrib.language.length > 0)
+          output ~= ".lang: " ~ obj.attrib.language;
+
+        /+ ↓ has flags +/
+        {
+          string[] has_flags;
+          if (obj.has.inline_links) has_flags ~= "links";
+          if (obj.has.inline_notes_reg) has_flags ~= "notes_reg";
+          if (obj.has.inline_notes_star) has_flags ~= "notes_star";
+          if (obj.has.images) has_flags ~= "images";
+          if (has_flags.length > 0)
+            output ~= ".has: " ~ has_flags.join(" ");
+        }
+
+        /+ ↓ table properties +/
+        if (obj.metainfo.is_a == "table" && obj.table.number_of_columns > 0) {
+          output ~= ".table_cols: " ~ obj.table.number_of_columns.to!string;
+          if (obj.table.column_widths.length > 0) {
+            string[] ws;
+            foreach (w; obj.table.column_widths) ws ~= w.to!string;
+            output ~= ".table_widths: " ~ ws.join(" ");
+          }
+          if (obj.table.heading)
+            output ~= ".table_header: true";
+        }
+
+        /+ ↓ code block properties +/
+        if (obj.metainfo.is_a == "code") {
+          if (obj.code_block.syntax.length > 0)
+            output ~= ".code_syntax: " ~ obj.code_block.syntax;
+          if (obj.code_block.linenumbers)
+            output ~= ".code_linenumbers: true";
+        }
+
+        /+ ↓ tag properties +/
+        if (obj.tags.in_segment_html.length > 0)
+          output ~= ".segment: " ~ obj.tags.in_segment_html;
+        if (obj.tags.anchor_tag_html.length > 0 && obj.tags.anchor_tag_html != obj.tags.in_segment_html)
+          output ~= ".anchor: " ~ obj.tags.anchor_tag_html;
+        if (obj.tags.segname_prev.length > 0)
+          output ~= ".segment_prev: " ~ obj.tags.segname_prev;
+        if (obj.tags.segname_next.length > 0)
+          output ~= ".segment_next: " ~ obj.tags.segname_next;
+
+        /+ ↓ text content +/
+        if (obj.text.length > 0) {
+          foreach (line; obj.text.split("\n")) {
+            output ~= "| " ~ line;
+          }
+        }
+
+        output ~= "";
+      }
+
+      output ~= "}";
+      output ~= "";
+    }
+
+    /+ ↓ write to file +/
+    auto out_pth = spineOutPaths!()(doc_matters.output_path, doc_matters.src.language);
+    string base_dir = "abstraction";
+    string base_pth = ((out_pth.output_base.chainPath(base_dir)).asNormalizedPath).array;
+    try {
+      if (!exists(base_pth)) {
+        base_pth.mkdirRecurse;
+      }
+    } catch (Exception ex) {
+    }
+    string out_file = ((base_pth.chainPath(
+      doc_matters.src.doc_uid_out ~ ".ssp")).asNormalizedPath).array;
+    if (doc_matters.opt.action.vox_gt_1) {
+      writeln(" ", out_file);
+    }
+    auto f = File(out_file, "w");
+    foreach (line; output) {
+      f.writeln(line);
+    }
+  }
+}
+#+END_SRC
+
+* org includes
+** project version
+
+#+NAME: spine_version
+#+HEADER: :noweb yes
+#+BEGIN_SRC emacs-lisp
+<<./sisudoc_spine_version_info_and_doc_header_including_copyright_and_license.org:spine_project_version()>>
+#+END_SRC
+
+** year
+
+#+NAME: year
+#+HEADER: :noweb yes
+#+BEGIN_SRC emacs-lisp
+<<./sisudoc_spine_version_info_and_doc_header_including_copyright_and_license.org:year()>>
+#+END_SRC
+
+** document header including copyright & license
+
+#+NAME: doc_header_including_copyright_and_license
+#+HEADER: :noweb yes
+#+BEGIN_SRC emacs-lisp
+<<./sisudoc_spine_version_info_and_doc_header_including_copyright_and_license.org:spine_doc_header_including_copyright_and_license()>>
+#+END_SRC
+
+* __END__
diff --git a/org/spine.org b/org/spine.org
index 40a89e9..1eef0a3 100644
--- a/org/spine.org
+++ b/org/spine.org
@@ -341,6 +341,7 @@ bool[string] opts = [
   "pdf-init"                    : false,
   "pod"                         : false,
   "serial"                      : false,
+  "show-abstraction"            : false,
   "show-config"                 : false,
   "show-curate"                 : false,
   "show-curate-authors"         : false,
@@ -476,6 +477,7 @@ auto helpInfo = getopt(args,
   "section-toc",                "table of contents (default)",                                    &opts["section_toc"],
   "serial",                     "serial processing",                                              &opts["serial"],
   "skip-output",                "skip output",                                                    &opts["skip-output"],
+  "show-abstraction",           "show document abstraction (write .ssp file)",                    &opts["show-abstraction"],
   "show-config",                "show config",                                                    &opts["show-config"],
   "show-curate",                "show curate",                                                    &opts["show-curate"],
   "show-curate-authors",        "show curate authors",                                            &opts["show-curate-authors"],
@@ -694,6 +696,9 @@ struct OptActions {
   @trusted bool show_config() {
     return opts["show-config"];
   }
+  @trusted bool show_abstraction() {
+    return opts["show-abstraction"];
+  }
   @trusted bool show_curate() {
     return opts["show-curate"];
   }
@@ -942,6 +947,7 @@ struct OptActions {
   @trusted bool abstraction() {
     return (
       opts["abstraction"]
+      || show_abstraction
       || concordance
       || source_or_pod
       || curate
@@ -968,6 +974,7 @@ struct OptActions {
       || latex
       || odt
       || manifest
+      || show_abstraction
       || show_make
       || show_metadata
       || show_summary
@@ -982,6 +989,7 @@ struct OptActions {
   @trusted bool meta_processing_general() {
     return (
       opts["abstraction"]
+      || show_abstraction
       || curate
       || html
       || epub
@@ -1535,6 +1543,7 @@ if ((doc.matters.opt.action.debug_do)
 <<spine_each_file_do_debugs_checkdoc_1>>
 <<spine_each_file_do_debugs_checkdoc_2>>
 <<spine_each_file_do_debugs_checkdoc_3>>
+<<spine_each_file_show_abstraction>>
 <<spine_each_file_do_debugs_checkdoc_4>>
 <<spine_each_file_do_debugs_checkdoc_5>>
 #+END_SRC
@@ -1586,6 +1595,18 @@ if (doc.matters.opt.action.show_config) {
 }
 #+END_SRC
 
+***** show abstraction (PEG)
+--show-abstraction
+
+#+NAME: spine_each_file_show_abstraction
+#+BEGIN_SRC d
+/+ ↓ document abstraction text representation +/
+if (doc.matters.opt.action.show_abstraction) {
+  import sisudoc.io_out.create_abstraction_txt;
+  spineAbstractionTxt!()(doc);
+}
+#+END_SRC
+
 ***** abstraction curate :abstraction:curate:
 - abstraction curate
 
diff --git a/src/sisudoc/io_out/create_abstraction_txt.d b/src/sisudoc/io_out/create_abstraction_txt.d
new file mode 100644
index 0000000..a1e8f12
--- /dev/null
+++ b/src/sisudoc/io_out/create_abstraction_txt.d
@@ -0,0 +1,304 @@
+/+
+- Name: SisuDoc Spine, Doc Reform [a part of]
+  - Description: documents, structuring, processing, publishing, search
+    - static content generator
+
+  - Author: Ralph Amissah
+    [ralph.amissah@gmail.com]
+
+  - Copyright: (C) 2015 (continuously updated, current 2026) Ralph Amissah, All Rights Reserved.
+
+  - License: AGPL 3 or later:
+
+    Spine (SiSU), a framework for document structuring, publishing and
+    search
+
+    Copyright (C) Ralph Amissah
+
+    This program is free software: you can redistribute it and/or modify it
+    under the terms of the GNU AFERO General Public License as published by the
+    Free Software Foundation, either version 3 of the License, or (at your
+    option) any later version.
+
+    This program is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+    more details.
+
+    You should have received a copy of the GNU General Public License along with
+    this program. If not, see [https://www.gnu.org/licenses/].
+
+    If you have Internet connection, the latest version of the AGPL should be
+    available at these locations:
+    [https://www.fsf.org/licensing/licenses/agpl.html]
+    [https://www.gnu.org/licenses/agpl.html]
+
+  - Spine (by Doc Reform, related to SiSU) uses standard:
+    - docReform markup syntax
+      - standard SiSU markup syntax with modified headers and minor modifications
+    - docReform object numbering
+      - standard SiSU object citation numbering & system
+
+  - Homepages:
+    [https://www.sisudoc.org]
+    [https://www.doc-reform.org]
+
+  - Git
+    [https://git.sisudoc.org/]
+
++/
+module sisudoc.io_out.create_abstraction_txt;
+@safe:
+
+/+ ↓ write document abstraction as human-readable .ssp text file +/
+template spineAbstractionTxt() {
+  import std.conv : to;
+  import std.file;
+  import std.path;
+  import std.stdio;
+  import std.string;
+  import std.array;
+  import sisudoc.io_out.paths_output;
+
+  void spineAbstractionTxt(D)(D doc) {
+    auto doc_abstraction = doc.abstraction;
+    auto doc_matters     = doc.matters;
+    string[] output;
+
+    /+ ↓ header comment +/
+    output ~= "% SiSU Document Abstraction v0.1";
+    output ~= "% Source: " ~ doc_matters.src.filename;
+    output ~= "";
+
+    /+ ↓ @meta block +/
+    output ~= "@meta {";
+    auto meta = doc_matters.conf_make_meta.meta;
+    if (meta.title_main.length > 0)
+      output ~= "  title.main: " ~ meta.title_main;
+    if (meta.title_subtitle.length > 0)
+      output ~= "  title.subtitle: " ~ meta.title_subtitle;
+    if (meta.title_full.length > 0)
+      output ~= "  title.full: " ~ meta.title_full;
+    if (meta.title_language.length > 0)
+      output ~= "  title.language: " ~ meta.title_language;
+    if (meta.creator_author.length > 0)
+      output ~= "  creator.author: " ~ meta.creator_author;
+    if (meta.creator_author_surname.length > 0)
+      output ~= "  creator.author_surname: " ~ meta.creator_author_surname;
+    if (meta.creator_author_surname_fn.length > 0)
+      output ~= "  creator.author_surname_fn: " ~ meta.creator_author_surname_fn;
+    if (meta.creator_author_email.length > 0)
+      output ~= "  creator.author_email: " ~ meta.creator_author_email;
+    if (meta.creator_illustrator.length > 0)
+      output ~= "  creator.illustrator: " ~ meta.creator_illustrator;
+    if (meta.creator_translator.length > 0)
+      output ~= "  creator.translator: " ~ meta.creator_translator;
+    if (meta.date_published.length > 0)
+      output ~= "  date.published: " ~ meta.date_published;
+    if (meta.date_created.length > 0)
+      output ~= "  date.created: " ~ meta.date_created;
+    if (meta.date_issued.length > 0)
+      output ~= "  date.issued: " ~ meta.date_issued;
+    if (meta.date_available.length > 0)
+      output ~= "  date.available: " ~ meta.date_available;
+    if (meta.date_modified.length > 0)
+      output ~= "  date.modified: " ~ meta.date_modified;
+    if (meta.date_valid.length > 0)
+      output ~= "  date.valid: " ~ meta.date_valid;
+    if (meta.rights_copyright.length > 0)
+      output ~= "  rights.copyright: " ~ meta.rights_copyright;
+    if (meta.rights_license.length > 0)
+      output ~= "  rights.license: " ~ meta.rights_license;
+    if (meta.classify_topic_register.length > 0)
+      output ~= "  classify.topic_register: " ~ meta.classify_topic_register;
+    if (meta.classify_subject.length > 0)
+      output ~= "  classify.subject: " ~ meta.classify_subject;
+    if (meta.classify_keywords.length > 0)
+      output ~= "  classify.keywords: " ~ meta.classify_keywords;
+    if (meta.classify_loc.length > 0)
+      output ~= "  classify.loc: " ~ meta.classify_loc;
+    if (meta.classify_dewey.length > 0)
+      output ~= "  classify.dewey: " ~ meta.classify_dewey;
+    if (meta.identifier_isbn.length > 0)
+      output ~= "  identifier.isbn: " ~ meta.identifier_isbn;
+    if (meta.identifier_oclc.length > 0)
+      output ~= "  identifier.oclc: " ~ meta.identifier_oclc;
+    if (meta.language_document.length > 0)
+      output ~= "  language.document: " ~ meta.language_document;
+    if (meta.notes_abstract.length > 0)
+      output ~= "  notes.abstract: " ~ meta.notes_abstract;
+    if (meta.notes_description.length > 0)
+      output ~= "  notes.description: " ~ meta.notes_description;
+    if (meta.notes_summary.length > 0)
+      output ~= "  notes.summary: " ~ meta.notes_summary;
+    output ~= "}";
+    output ~= "";
+
+    /+ ↓ @make block +/
+    output ~= "@make {";
+    auto make = doc_matters.conf_make_meta.make;
+    if (make.doc_type.length > 0)
+      output ~= "  doc_type: " ~ make.doc_type;
+    if (make.auto_num_top_at_level.length > 0)
+      output ~= "  auto_num_top_at_level: " ~ make.auto_num_top_at_level;
+    output ~= "  auto_num_top_lv: " ~ make.auto_num_top_lv.to!string;
+    output ~= "  auto_num_depth: " ~ make.auto_num_depth.to!string;
+    output ~= "}";
+    output ~= "";
+
+    /+ ↓ @doc_has block +/
+    output ~= "@doc_has {";
+    output ~= "  inline_links: " ~ doc_matters.has.inline_links.to!string;
+    output ~= "  inline_notes_reg: " ~ doc_matters.has.inline_notes_reg.to!string;
+    output ~= "  inline_notes_star: " ~ doc_matters.has.inline_notes_star.to!string;
+    output ~= "  tables: " ~ doc_matters.has.tables.to!string;
+    output ~= "  codeblocks: " ~ doc_matters.has.codeblocks.to!string;
+    output ~= "  images: " ~ doc_matters.has.images.to!string;
+    output ~= "  poems: " ~ doc_matters.has.poems.to!string;
+    output ~= "  groups: " ~ doc_matters.has.groups.to!string;
+    output ~= "  blocks: " ~ doc_matters.has.blocks.to!string;
+    output ~= "  quotes: " ~ doc_matters.has.quotes.to!string;
+    output ~= "}";
+    output ~= "";
+
+    /+ ↓ document sections +/
+    string[] section_order = ["head", "toc", "body", "endnotes",
+      "glossary", "bibliography", "bookindex", "blurb"];
+
+    foreach (section; section_order) {
+      if (section !in doc_abstraction) continue;
+      auto section_objs = doc_abstraction[section];
+      if (section_objs.length == 0) continue;
+
+      output ~= "@" ~ section ~ " {";
+      output ~= "";
+
+      foreach (obj; section_objs) {
+        /+ ↓ object declaration line +/
+        string obj_decl = "[" ~ obj.metainfo.ocn.to!string ~ "] ";
+
+        if (obj.metainfo.is_a == "heading") {
+          string lev = obj.metainfo.marked_up_level;
+          obj_decl ~= "heading :" ~ lev;
+          if (obj.metainfo.identifier.length > 0) {
+            obj_decl ~= " " ~ obj.metainfo.identifier;
+          }
+        } else {
+          obj_decl ~= obj.metainfo.is_a;
+        }
+        output ~= obj_decl;
+
+        /+ ↓ properties (only non-default values) +/
+        if (obj.metainfo.is_of_part.length > 0)
+          output ~= ".part: " ~ obj.metainfo.is_of_part;
+        if (obj.metainfo.is_of_section.length > 0 && obj.metainfo.is_of_section != section)
+          output ~= ".section: " ~ obj.metainfo.is_of_section;
+        if (obj.metainfo.parent_ocn != 0)
+          output ~= ".parent: " ~ obj.metainfo.parent_ocn.to!string;
+        if (obj.metainfo.last_descendant_ocn != 0)
+          output ~= ".last_descendant: " ~ obj.metainfo.last_descendant_ocn.to!string;
+
+        /+ ↓ ancestors (only if non-zero) +/
+        bool has_ancestors = false;
+        foreach (a; obj.metainfo.markedup_ancestors) {
+          if (a != 0) { has_ancestors = true; break; }
+        }
+        if (has_ancestors) {
+          string anc;
+          foreach (i, a; obj.metainfo.markedup_ancestors) {
+            if (i > 0) anc ~= " ";
+            anc ~= a.to!string;
+          }
+          output ~= ".ancestors: " ~ anc;
+        }
+
+        if (obj.metainfo.dummy_heading)
+          output ~= ".dummy: true";
+        if (obj.metainfo.object_number_off)
+          output ~= ".ocn_off: true";
+
+        /+ ↓ text attributes +/
+        if (obj.attrib.indent_base != 0 || obj.attrib.indent_hang != 0)
+          output ~= ".indent: " ~ obj.attrib.indent_base.to!string
+            ~ " " ~ obj.attrib.indent_hang.to!string;
+        if (obj.attrib.bullet)
+          output ~= ".bullet: true";
+        if (obj.attrib.language.length > 0)
+          output ~= ".lang: " ~ obj.attrib.language;
+
+        /+ ↓ has flags +/
+        {
+          string[] has_flags;
+          if (obj.has.inline_links) has_flags ~= "links";
+          if (obj.has.inline_notes_reg) has_flags ~= "notes_reg";
+          if (obj.has.inline_notes_star) has_flags ~= "notes_star";
+          if (obj.has.images) has_flags ~= "images";
+          if (has_flags.length > 0)
+            output ~= ".has: " ~ has_flags.join(" ");
+        }
+
+        /+ ↓ table properties +/
+        if (obj.metainfo.is_a == "table" && obj.table.number_of_columns > 0) {
+          output ~= ".table_cols: " ~ obj.table.number_of_columns.to!string;
+          if (obj.table.column_widths.length > 0) {
+            string[] ws;
+            foreach (w; obj.table.column_widths) ws ~= w.to!string;
+            output ~= ".table_widths: " ~ ws.join(" ");
+          }
+          if (obj.table.heading)
+            output ~= ".table_header: true";
+        }
+
+        /+ ↓ code block properties +/
+        if (obj.metainfo.is_a == "code") {
+          if (obj.code_block.syntax.length > 0)
+            output ~= ".code_syntax: " ~ obj.code_block.syntax;
+          if (obj.code_block.linenumbers)
+            output ~= ".code_linenumbers: true";
+        }
+
+        /+ ↓ tag properties +/
+        if (obj.tags.in_segment_html.length > 0)
+          output ~= ".segment: " ~ obj.tags.in_segment_html;
+        if (obj.tags.anchor_tag_html.length > 0 && obj.tags.anchor_tag_html != obj.tags.in_segment_html)
+          output ~= ".anchor: " ~ obj.tags.anchor_tag_html;
+        if (obj.tags.segname_prev.length > 0)
+          output ~= ".segment_prev: " ~ obj.tags.segname_prev;
+        if (obj.tags.segname_next.length > 0)
+          output ~= ".segment_next: " ~ obj.tags.segname_next;
+
+        /+ ↓ text content +/
+        if (obj.text.length > 0) {
+          foreach (line; obj.text.split("\n")) {
+            output ~= "| " ~ line;
+          }
+        }
+
+        output ~= "";
+      }
+
+      output ~= "}";
+      output ~= "";
+    }
+
+    /+ ↓ write to file +/
+    auto out_pth = spineOutPaths!()(doc_matters.output_path, doc_matters.src.language);
+    string base_dir = "abstraction";
+    string base_pth = ((out_pth.output_base.chainPath(base_dir)).asNormalizedPath).array;
+    try {
+      if (!exists(base_pth)) {
+        base_pth.mkdirRecurse;
+      }
+    } catch (Exception ex) {
+    }
+    string out_file = ((base_pth.chainPath(
+      doc_matters.src.doc_uid_out ~ ".ssp")).asNormalizedPath).array;
+    if (doc_matters.opt.action.vox_gt_1) {
+      writeln(" ", out_file);
+    }
+    auto f = File(out_file, "w");
+    foreach (line; output) {
+      f.writeln(line);
+    }
+  }
+}
diff --git a/src/sisudoc/spine.d b/src/sisudoc/spine.d
index fcde22e..ceb9d6c 100755
--- a/src/sisudoc/spine.d
+++ b/src/sisudoc/spine.d
@@ -166,6 +166,7 @@ string program_name = "spine";
     "pdf-init"                    : false,
     "pod"                         : false,
     "serial"                      : false,
+    "show-abstraction"            : false,
     "show-config"                 : false,
     "show-curate"                 : false,
     "show-curate-authors"         : false,
@@ -287,6 +288,7 @@ string program_name = "spine";
     "section-toc",                "table of contents (default)",                                    &opts["section_toc"],
     "serial",                     "serial processing",                                              &opts["serial"],
     "skip-output",                "skip output",                                                    &opts["skip-output"],
+    "show-abstraction",           "show document abstraction (write .ssp file)",                    &opts["show-abstraction"],
     "show-config",                "show config",                                                    &opts["show-config"],
     "show-curate",                "show curate",                                                    &opts["show-curate"],
     "show-curate-authors",        "show curate authors",                                            &opts["show-curate-authors"],
@@ -498,6 +500,9 @@ string program_name = "spine";
     @trusted bool show_config() {
       return opts["show-config"];
     }
+    @trusted bool show_abstraction() {
+      return opts["show-abstraction"];
+    }
     @trusted bool show_curate() {
       return opts["show-curate"];
     }
@@ -746,6 +751,7 @@ string program_name = "spine";
     @trusted bool abstraction() {
       return (
         opts["abstraction"]
+        || show_abstraction
         || concordance
         || source_or_pod
         || curate
@@ -772,6 +778,7 @@ string program_name = "spine";
         || latex
         || odt
         || manifest
+        || show_abstraction
         || show_make
         || show_metadata
         || show_summary
@@ -786,6 +793,7 @@ string program_name = "spine";
     @trusted bool meta_processing_general() {
       return (
         opts["abstraction"]
+        || show_abstraction
         || curate
         || html
         || epub
@@ -1303,6 +1311,11 @@ string program_name = "spine";
             import sisudoc.meta.metadoc_show_config;
             spineShowConfig!()(doc.matters);
           }
+          /+ ↓ document abstraction text representation +/
+          if (doc.matters.opt.action.show_abstraction) {
+            import sisudoc.io_out.create_abstraction_txt;
+            spineAbstractionTxt!()(doc);
+          }
           if (doc.matters.opt.action.curate) {
             auto _hvst = spineMetaDocCurate!()(doc.matters, hvst);
             if (
@@ -1402,6 +1415,11 @@ string program_name = "spine";
             import sisudoc.meta.metadoc_show_config;
             spineShowConfig!()(doc.matters);
           }
+          /+ ↓ document abstraction text representation +/
+          if (doc.matters.opt.action.show_abstraction) {
+            import sisudoc.io_out.create_abstraction_txt;
+            spineAbstractionTxt!()(doc);
+          }
           if (doc.matters.opt.action.curate) {
             auto _hvst = spineMetaDocCurate!()(doc.matters, hvst);
             if (