indd-utils/docs/format/footnotes.md

Footnotes and endnotes

Footnotes, endnotes and their document options. Implemented in src/model/story.rs (text), src/model/prefs.rs (options) and src/idml/story.rs, designmap.rs, resources.rs (writing).

Class	Object	IDML element
0x24F	Footnote	Footnote (story text)
0x2801	Endnote story	Story with IsEndnoteStory="true"
0x2805	Endnote	Endnote (story text)
0x2804	Endnote range	EndnoteRange (endnote story text)

Counts are over the little-endian corpus without the privately held samples, unless they name the trustworthy pairs (measurement.md).

Footnotes

Reference. A footnote reference is a U+0004 character in story or table cell text. The owned-items strand (run kind 0x209, objects.md) lists an object of class 0x24F, the footnote, at that position. 14,026 footnotes in 391 files, InDesign 5 to 21, are all at a U+0004: 14,002 in story text and 24 in table cell text. In the pairs, the 819 Footnote elements of the IDML are in place of exactly these characters; the count per story matches in 47 of 47 stories.

Text. The footnote's text is in the same story text, after the story's own text, as table cell text is (tables.md). The text-owner strand (run kind 0x2A4) gives it the footnote UID as owner and 1 as the cell field. In all 14,026 footnotes the text is one stretch, its cell field is 1, and it ends with U+000D. 14,001 footnote texts contain one U+0004, the footnote number, which IDML writes as <?ACE 4?>; the other 25 have none. 261 footnote texts contain an anchored object (U+FFFC) and 1 contains a table.

IDML. IDML writes a Footnote element, without Self or attributes, in place of the reference character, inside the CharacterStyleRange of that position. The Footnote holds ParagraphStyleRange elements built from the footnote text, like a table cell; the final U+000D is not written. Evidence: the footnote texts of a story in the INDD equal the IDML footnote texts of that story in 819 of 819 footnotes (47 stories, 46 pairs), compared as multisets with U+0004, U+0018, U+FEFF and U+FFFC left out; the sequence of paragraph styles matches in 498 of 499 footnotes of the trustworthy pairs. Inside footnotes IDML has hyperlink sources (182 in a character range, 315 in a paragraph range), page references (33) and cross-reference sources (25); the converter places sources in footnotes by the rules of hyperlinks.md.

A U+0004 without a footnote or endnote object stays <?ACE 4?>, as in IDML: footnote numbers inside footnote and endnote text, and one pasted number in a 17.4 pair.

With this, 8 more stories of the trustworthy pairs have identical text, and their text ranges are compared.

Footnote options (preferences chunk 0x2820)

Chunk 0x2820 of the preferences object (class 0x2202) holds the document's FootnoteOption. It is 231 bytes in InDesign 7 to 11 and 233 bytes from 12 on, longer when the strings are longer, and missing in 90 of the 733 pairs collected. 643 files have the chunk and a FootnoteOption in their IDML, 442 of them trustworthy pairs; every attribute decoded below matches in 442 of 442 trustworthy pairs. Over all 643 files there are 4 mismatches, all in stale pairs (EnableStraddling in 3 files from 12.0, and a RuleColor).

Offset	Type	IDML
0	u32 character style UID	FootnoteMarkerStyle
4	u32 paragraph style UID	FootnoteTextStyle
8	u32 code	FootnoteNumberingStyle: 0xCA07 Arabic (641), 0xCA0A Symbols (1), 0xCA58 Asterisks (1)
12	u32	StartAt
16	u16	RestartNumbering: 0 DontRestart (641), 1 PageRestart (2)
18, 22	u16, u16	MarkerPositioning: (1, 0) SuperscriptMarker (635), (0, 0) NormalMarker (4), (0, 1) RubyMarker (4)
20	u16	0 in all
24	f64	SpaceBetween
32	f64	Spacer
40	u16	EosPlacement (1 true): 21 files true, 1,364 false, all matching (corpus of 2026-10)
42	u16	ShowPrefixSuffix: 0 NoPrefixSuffix (640), 1 PrefixSuffixReference (1), 3 PrefixSuffixBoth (2)
44	string	Prefix
	string	Suffix
	string	SeparatorText (tab, U+3000, U+2002, U+2003 and . seen)

A string here is a u32 length in UTF-16 units followed by text segments (objects.md), not the in-object string form.

The tail follows the separator: 172 bytes in files from InDesign 7 to 11, 174 bytes from 12 on. Offsets are from the start of the tail.

Offset	Type	IDML
0	u16	NoSplitting
4	f64	FootnoteMinimumFirstBaselineOffset: 19.84 in one file, 0 in the 1,384 others with a known tail, all matching (corpus of 2026-10)
12	u16, 174-byte tail only	EnableStraddling (317 of 317 trustworthy pairs)
R	rule block, 78 bytes	Rule…
R + 78	the same block	ContinuingRule…

R is 18 for a 174-byte tail and 16 for a 172-byte tail. Each block:

Block offset	Type	IDML (Rule or ContinuingRule prefix)
0	u16	…On
2	u32 code, then u32 0	…Type, as the stroke types of page items and cells: 0x5A29 StrokeStyle/$ID/Solid, 0x5A39 …/Canned Dotted, 0xB007 …/ThickThick
10	u32 swatch UID	…Color
14	f64	…LineWeight
22	f64	…Tint
30	u16	0 in all
32	u32 swatch UID	…GapColor
36	f64	…GapTint
44	2 bytes	0 in all; the two overprint flags are false in all, so they cannot be told apart
46	f64	…LeftIndent
54	f64	…Width
62	f64	…Offset
70	8 bytes	0 in all

A tail of another length is not read: the converter keeps the observed values for the rules and warns. Codes not listed are left out. FootnoteFirstBaselineOffset and the overprint flags have one value in every sample and come from the generated value file (idml-values.md).

Without the chunk (90 files) the IDML has the defaults of the value file, FootnoteTextStyle="ParagraphStyle/$ID/NormalParagraphStyle", SeparatorText tab, and EnableStraddling="true" from DOM 12 (67 of 67). In the corpus of 2026-10 the 75 files without the chunk (51 trustworthy) also have, each in 75 of 75: StartAt="1", Prefix="", Suffix="", FootnoteMarkerStyle="CharacterStyle/$ID/[No character style]", SeparatorText tab, SpaceBetween="0", Spacer="0", FootnoteMinimumFirstBaselineOffset="0", EosPlacement="false", NoSplitting="false"; for the rule and the continuing rule …On true, …LineWeight 1, …Tint and …GapTint 100, …LeftIndent 0, …Width 72 (rule) and 288 (continuing rule), …Offset 0, …Type StrokeStyle/$ID/Solid, …Color Color/Black, …GapColor Swatch/None; and the properties FootnoteNumberingStyle Arabic, RestartNumbering DontRestart, ShowPrefixSuffix NoPrefixSuffix and MarkerPositioning SuperscriptMarker. The value files lost most of these when the corpus grew, because files with the chunk vary; the converter writes them for files without the chunk.

The 75 files without the chunk all have a last session with language code 0x0100 or 0x0103 (objects.md, save history), so whether a Japanese edition writes another separator without the chunk, as it does for endnotes (endnote options, below), is not shown.

In the trustworthy pairs every FootnoteOption value is reproduced (489 of 489 pairs for each attribute).

Text frame footnote options

TextFrameFootnoteOptionsObject is a child of TextFrame in IDML from DOM 12, with EnableOverrides, SpanFootnotesAcross, MinimumSpacingOption and SpaceBetweenFootnotes: the frame's FootnotesEnableOverrides, FootnotesSpanAcrossColumns, FootnotesMinimumSpacing and FootnotesSpaceBetween.

IDML writes it on a frame of DOM 12 or later when one of these holds:

• the frame's applied object style lacks category 0xADCA (footnotes) in its category list (chunk 0x1B92E; objects.md, text frame preferences);
• the frame's footnote values (span, minimum spacing, space between) differ from the style's;
• the frame has no object style object.

This is the rule TextFramePreference follows for its Footnotes… attributes, applied from DOM 12 although TextFramePreference has no footnote values before 13.1. The frame's values are in chunk 0x22608 of its multi-column frame (objects.md, text frame preferences): u16 at 2 the span (1 = true), f64 at 4 and 12 the spacings. Without the chunk they are false, 12 and 6. The style's values are those of its text frame settings (chunk 0x1B924: u16 at 144, f64 at 146 and 154), or of the style it is based on, or false, 12 and 6.

Evidence: measured on 16,900 text frames of DOM 12 or later in 606 trustworthy pairs before 2026-10 (every frame with the category off or without a style has the element, 6,011 of 6,011; every frame with the category on and equal values has none, 10,888 of 10,888; the one frame with the category on and other values has it). Over the 1,251 trustworthy pairs after 2026-10, the converter's elements by this rule are 20,096 of the 20,096 reference elements on the frames it writes, with all four values, and no element that the reference lacks; the other 255 are on frames it does not write. Three elements of the output have an EnableOverrides that the reference element lacks (not explained).

EnableOverrides is false in every element. Chunk 0x22608 has a u16 0 at offset 0 in every sample; it is probably that flag, which no sample shows set. The converter writes false. The element follows TextFramePreference and the frame's BaselineFrameGridOption.

Endnotes

Endnote story. Document chunk 0x22618 is a u32, the UID of the endnote story, class 0x2801 (12 of 12 files with endnotes). The story is listed in document chunk 0x222 with the other stories and has the same strands as a class 0x201 story. IDML lists it in StoryList in that order and writes it as a Story with IsEndnoteStory="true". One per file; 729 endnotes in 12 files (InDesign 16.2, 17.2, 20.0 and 21.2).

Reference. An endnote reference is a U+0004 in story text. The owned-items strand lists an object of class 0x2805 at that position (729 of 729). IDML writes, in place of the character, <Endnote Self="u<0x2805 UID>" EndnoteTextRange="u<0x2804 UID>"/>.

Endnote objects. Class 0x2805, chunk 0x22616: u32 UID of its range (class 0x2804). Class 0x2804, chunk 0x2261A: u32 UID of its endnote. The two point at each other in 729 of 729.

Range position. The endnote story's strand of class 0xCA1C holds a range tree (hyperlinks.md, position in the text) whose node sources are the 0x2804 objects: 729 nodes for 729 endnotes. The same tree also holds 15 hyperlink text sources (class 0x13502). The range text starts with U+FEFF U+0004 (710 of 729), ends with U+FEFF (729 of 729) and holds a paragraph return in 13 of 729. IDML writes <EndnoteRange Self="u<0x2804 UID>" SourceEndnote="u<0x2805 UID>"> around the range, both U+FEFF included in Content: inside one CharacterStyleRange when the range lies in one (2 ranges in a 21.2 pair), or as a child of the ParagraphStyleRange around several (1 range in a 17.2 file with a DOM 14 IDML). How IDML writes a range across paragraphs is not shown. The converter writes ranges within one character range and leaves out the wrapper of others, with a warning.

Endnote text frame. A text frame whose story is the endnote story is written as EndnoteTextFrame, with the attributes and children of a TextFrame (1 frame, compared attribute by attribute).

Schema. The 21.5 schema rejects InDesign's own endnote markup: Endnote is allowed only directly in Story, Cell and similar places, not in CharacterStyleRange, and EndnoteRange is defined without content. Jing reports both on the reference IDML. The converter writes the markup as InDesign does; measurement.md describes the validation exception.

Endnote options (preferences chunk 0x2261E)

Fields in order:

1. string EndnoteTitle
2. u32 EndnoteTitleStyle (paragraph style UID)
3. u32 numbering code (0xCA07 Arabic, the only value)
4. u32 StartEndnoteNumberAt
5. u32 restart (0 Continuous, the only value)
6. u32 EndnoteMarkerPositioning: 1 SuperscriptMarker, 3 RubyMarker
7. u32 EndnoteMarkerStyle (character style UID)
8. u32 EndnoteTextStyle (paragraph style UID)
9. string EndnoteSeparatorText
10. u32 (1 in all)
11. u32 (1 in all)
12. string (empty in all)
13. string (empty in all)
14. u32 (0 in all)

Strings are as in chunk 0x2820. 359 files have the chunk and an EndnoteOption in their IDML (240 trustworthy): all values match in all 359, and the parse ends at the end of the chunk. Fields 10 to 14 never vary (ScopeValue EndnoteDocumentScope, FrameCreateOption NewPage, EndnotePrefix, EndnoteSuffix, ShowEndnotePrefixSuffix NoPrefixSuffix), so which is which is not proven; their values come from the value file.

Without the chunk (149 files with DOM 13 or later) the marker and text styles are the defaults, which the converter writes. The title is the exporting InDesign's localized default (Endnotes 108, Notes de fin 18, Eindnoten 12, 4 others in the 654 pairs before 2026-10), and the separator and marker position follow its language. The converter writes the separator U+3000 when the last session of the save history has language code 0x0101, and tab otherwise (140 of 141 pairs before 2026-10; objects.md, save history). Over all pairs of the corpus of 2026-10 without the chunk this gives 258 of 273 separators (211 of 226 trustworthy). Of the 15 others, 13 have code 0x0101 and tab, and their IDML has the values of a Roman edition in the preferences too (LightBlue baseline grid, Violet column guides; preferences.md, values of the exporting edition): they were exported by another installation. One Japanese document of code 0x0101 has tab and one Korean document of code 0x0100 has U+3000; no stored value separates them. The title and the marker position follow the saving edition that the XMP black name shows (objects.md, saving edition): RubyMarker for a Japanese edition only, so Korean editions, which also have code 0x0101, get SuperscriptMarker. Over the trustworthy pairs of the corpus after 2026-10 this gives 917 of 918 titles and 916 of 918 marker positions (692 and 876 before); without a black name the marker follows the code.

IsEndnoteStory

IsEndnoteStory is on every Story and XmlStory from DOM 13: 0 of 2,467 stories and 0 of 39 XML stories in DOM 12 IDML, 3,094 of 3,094 and 173 of 173 in DOM 13.0–14.0.