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pdftract/notes/bf-41gtd.md
jedarden 76a66cd24e docs(bf-41gtd): document selected unmapped glyphs for fixture 
Selected 4 unmapped glyphs from distinct categories:
- /g001 (PUA glyph)
- /CustomA (custom encoding)
- /glyph_0041 (algorithmic pattern outside AGL)
- /NotAGlyph (orphaned character code)

Plus 3 mapped AGL glyphs for comparison (/A, /space, /B).

Each unmapped glyph documented with why it fails all 4 mapping levels.
Fixture design includes content stream byte sequence and expected output.
2026-07-03 18:52:42 -04:00

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Selected Unmapped Glyphs for Fixture

Task: Select target unmapped glyphs for fixture Bead ID: bf-41gtd Date: 2026-07-03 Based on: notes/bf-1cvmt.md

Overview

This document selects specific unmapped glyphs for the PDF fixture, drawn from the research in bf-1cvmt. The fixture will include 4 unmapped glyphs (from different categories) and 3 mapped AGL glyphs for comparison.

Selected Unmapped Glyphs (4 examples)

1. /g001 - Private Use Area (PUA) Glyph

Category: Private Use Area (PUA) Glyphs Source: tests/fixtures/encoding/no-mapping.pdf

Why unmapped (fails all 4 levels):

  • Level 1 (ToUnicode): No /ToUnicode CMap exists
  • Level 2 (AGL): Glyph name /g001 is not in the Adobe Glyph List
  • Level 3 (Fingerprint): Font not in fingerprint database
  • Level 4 (Shape): Shape recognition disabled or no match

Context: Uses custom encoding with /Differences [0 /g001 /g002 /g003]

2. /CustomA - Custom Encoding Without Standard Names

Category: Custom Encodings Without Standard Names Source: Pattern from bf-1cvmt research

Why unmapped (fails all 4 levels):

  • Level 1 (ToUnicode): No /ToUnicode CMap exists
  • Level 2 (AGL): Glyph name /CustomA is not in the Adobe Glyph List
  • Level 3 (Fingerprint): Font not in fingerprint database
  • Level 4 (Shape): Shape recognition disabled or no match

Context: Would appear in custom encoding like /Differences [65 /CustomA 66 /CustomB]

3. /glyph_0041 - Algorithmic Pattern Outside AGL Convention

Category: Algorithmic Patterns Outside AGL Convention Source: Pattern from bf-1cvmt research

Why unmapped (fails all 4 levels):

  • Level 1 (ToUnicode): No /ToUnicode CMap exists
  • Level 2 (AGL): Glyph name /glyph_0041 doesn't match AGL patterns (uniXXXX or uXXXXXX)
  • Level 3 (Fingerprint): Font not in fingerprint database
  • Level 4 (Shape): Shape recognition disabled or no match

Context: AGL only recognizes uniXXXX (exactly 4 hex digits) or uXXXXXX (up to 6 hex digits) patterns. The prefix /glyph_ is not recognized.

4. /NotAGlyph - Orphaned Character Code

Category: Orphaned Character Codes Source: Pattern from bf-1cvmt research

Why unmapped (fails all 4 levels):

  • Level 1 (ToUnicode): No /ToUnicode CMap exists
  • Level 2 (AGL): Glyph name /NotAGlyph is not in the Adobe Glyph List
  • Level 3 (Fingerprint): Font not in fingerprint database
  • Level 4 (Shape): Shape recognition disabled or no match

Context: Would appear in encoding like /Differences [32 /space 999 /NotAGlyph], where the code may be outside valid range (0-255).

Selected Mapped Glyphs (3 examples for comparison)

1. /A - Standard AGL Glyph

Category: Adobe Glyph List (AGL) mapped Unicode: U+0041 (LATIN CAPITAL LETTER A)

Why mapped:

  • Level 2 (AGL): Glyph name /A is found in the Adobe Glyph List with mapping to U+0041
  • Confidence: 0.9 (if Level 1 fails)

AGL entry: From crates/pdftract-core/src/font/agl.rs

2. /space - Standard AGL Glyph

Category: Adobe Glyph List (AGL) mapped Unicode: U+0020 (SPACE)

Why mapped:

  • Level 2 (AGL): Glyph name /space is found in the Adobe Glyph List with mapping to U+0020
  • Confidence: 0.9 (if Level 1 fails)

AGL entry: From crates/pdftract-core/src/font/agl.rs

3. /B - Standard AGL Glyph

Category: Adobe Glyph List (AGL) mapped Unicode: U+0042 (LATIN CAPITAL LETTER B)

Why mapped:

  • Level 2 (AGL): Glyph name /B is found in the Adobe Glyph List with mapping to U+0042
  • Confidence: 0.9 (if Level 1 fails)

AGL entry: From crates/pdftract-core/src/font/agl.rs

Fixture Design Implications

Content Stream Byte Sequence

The fixture should use a content stream with byte codes that map to both unmapped and mapped glyphs:

/Differences [
  0 /g001           % code 0 → unmapped (PUA)
  1 /CustomA        % code 1 → unmapped (custom)
  32 /space         % code 32 → mapped (U+0020)
  65 /A             % code 65 → mapped (U+0041)
  66 /B             % code 66 → mapped (U+0042)
  99 /glyph_0041    % code 99 → unmapped (bad algorithmic)
  100 /NotAGlyph    % code 100 → unmapped (orphaned)
]

Content stream text: <00 01 20 41 42 63 64> TJ

Expected output: <EFBFBD><EFBFBD><EFBFBD> ABC<42><43> (U+FFFD for codes 0, 1, 99, 100; standard glyphs for 32, 65, 66)

Expected Diagnostic Count

The fixture should emit 4 GLYPH_UNMAPPED diagnostics (one per unmapped glyph):

  1. GLYPH_UNMAPPED for glyph /g001 at code 0x00
  2. GLYPH_UNMAPPED for glyph /CustomA at code 0x01
  3. GLYPH_UNMAPPED for glyph /glyph_0041 at code 0x63
  4. GLYPH_UNMAPPED for glyph /NotAGlyph at code 0x64

Why These Particular Glyphs

  1. Coverage: They represent 4 distinct unmapped glyph categories from bf-1cvmt research
  2. Test value: Each fails all 4 mapping levels for a different reason
    • /g001: Arbitrary PUA naming
    • /CustomA: Custom encoding fabrication
    • /glyph_0041: Looks algorithmic but uses wrong prefix
    • /NotAGlyph: Orphaned name reference
  3. Comparison: Mapped glyphs /space, /A, /B provide baseline for Level 2 (AGL) success
  4. Fixture simplicity: All glyphs fit in single-byte encoding (0-255 range)

Next Steps

After this bead, the fixture should be generated using the encoding fixture generator at tests/fixtures/encoding/generate_unicode_recovery_fixtures.rs or a similar generator.

References

  • Research notes: notes/bf-1cvmt.md
  • Font resolver: crates/pdftract-core/src/font/resolver.rs (lines 285-376)
  • AGL lookup: crates/pdftract-core/src/font/agl.rs
  • Diagnostics: crates/pdftract-core/src/diagnostics.rs (lines 569-576)
  • Example fixture: tests/fixtures/encoding/no-mapping.pdf