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.
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notes/bf-41gtd.md
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# Selected Unmapped Glyphs for Fixture
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**Task:** Select target unmapped glyphs for fixture
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**Bead ID:** bf-41gtd
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**Date:** 2026-07-03
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**Based on:** notes/bf-1cvmt.md
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## Overview
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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.
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## Selected Unmapped Glyphs (4 examples)
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### 1. `/g001` - Private Use Area (PUA) Glyph
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**Category:** Private Use Area (PUA) Glyphs
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**Source:** tests/fixtures/encoding/no-mapping.pdf
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**Why unmapped (fails all 4 levels):**
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- Level 1 (ToUnicode): No `/ToUnicode` CMap exists
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- Level 2 (AGL): Glyph name `/g001` is not in the Adobe Glyph List
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- Level 3 (Fingerprint): Font not in fingerprint database
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- Level 4 (Shape): Shape recognition disabled or no match
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**Context:** Uses custom encoding with `/Differences [0 /g001 /g002 /g003]`
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---
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### 2. `/CustomA` - Custom Encoding Without Standard Names
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**Category:** Custom Encodings Without Standard Names
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**Source:** Pattern from bf-1cvmt research
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**Why unmapped (fails all 4 levels):**
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- Level 1 (ToUnicode): No `/ToUnicode` CMap exists
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- Level 2 (AGL): Glyph name `/CustomA` is not in the Adobe Glyph List
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- Level 3 (Fingerprint): Font not in fingerprint database
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- Level 4 (Shape): Shape recognition disabled or no match
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**Context:** Would appear in custom encoding like `/Differences [65 /CustomA 66 /CustomB]`
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---
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### 3. `/glyph_0041` - Algorithmic Pattern Outside AGL Convention
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**Category:** Algorithmic Patterns Outside AGL Convention
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**Source:** Pattern from bf-1cvmt research
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**Why unmapped (fails all 4 levels):**
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- Level 1 (ToUnicode): No `/ToUnicode` CMap exists
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- Level 2 (AGL): Glyph name `/glyph_0041` doesn't match AGL patterns (`uniXXXX` or `uXXXXXX`)
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- Level 3 (Fingerprint): Font not in fingerprint database
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- Level 4 (Shape): Shape recognition disabled or no match
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**Context:** AGL only recognizes `uniXXXX` (exactly 4 hex digits) or `uXXXXXX` (up to 6 hex digits) patterns. The prefix `/glyph_` is not recognized.
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---
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### 4. `/NotAGlyph` - Orphaned Character Code
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**Category:** Orphaned Character Codes
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**Source:** Pattern from bf-1cvmt research
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**Why unmapped (fails all 4 levels):**
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- Level 1 (ToUnicode): No `/ToUnicode` CMap exists
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- Level 2 (AGL): Glyph name `/NotAGlyph` is not in the Adobe Glyph List
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- Level 3 (Fingerprint): Font not in fingerprint database
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- Level 4 (Shape): Shape recognition disabled or no match
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**Context:** Would appear in encoding like `/Differences [32 /space 999 /NotAGlyph]`, where the code may be outside valid range (0-255).
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---
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## Selected Mapped Glyphs (3 examples for comparison)
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### 1. `/A` - Standard AGL Glyph
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**Category:** Adobe Glyph List (AGL) mapped
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**Unicode:** U+0041 (LATIN CAPITAL LETTER A)
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**Why mapped:**
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- Level 2 (AGL): Glyph name `/A` is found in the Adobe Glyph List with mapping to U+0041
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- Confidence: 0.9 (if Level 1 fails)
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**AGL entry:** From `crates/pdftract-core/src/font/agl.rs`
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---
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### 2. `/space` - Standard AGL Glyph
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**Category:** Adobe Glyph List (AGL) mapped
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**Unicode:** U+0020 (SPACE)
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**Why mapped:**
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- Level 2 (AGL): Glyph name `/space` is found in the Adobe Glyph List with mapping to U+0020
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- Confidence: 0.9 (if Level 1 fails)
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**AGL entry:** From `crates/pdftract-core/src/font/agl.rs`
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---
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### 3. `/B` - Standard AGL Glyph
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**Category:** Adobe Glyph List (AGL) mapped
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**Unicode:** U+0042 (LATIN CAPITAL LETTER B)
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**Why mapped:**
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- Level 2 (AGL): Glyph name `/B` is found in the Adobe Glyph List with mapping to U+0042
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- Confidence: 0.9 (if Level 1 fails)
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**AGL entry:** From `crates/pdftract-core/src/font/agl.rs`
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---
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## Fixture Design Implications
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### Content Stream Byte Sequence
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The fixture should use a content stream with byte codes that map to both unmapped and mapped glyphs:
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```
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/Differences [
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0 /g001 % code 0 → unmapped (PUA)
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1 /CustomA % code 1 → unmapped (custom)
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32 /space % code 32 → mapped (U+0020)
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65 /A % code 65 → mapped (U+0041)
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66 /B % code 66 → mapped (U+0042)
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99 /glyph_0041 % code 99 → unmapped (bad algorithmic)
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100 /NotAGlyph % code 100 → unmapped (orphaned)
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]
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```
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Content stream text: `<00 01 20 41 42 63 64> TJ`
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**Expected output:** `<60><><EFBFBD> ABC<42><43>` (U+FFFD for codes 0, 1, 99, 100; standard glyphs for 32, 65, 66)
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### Expected Diagnostic Count
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The fixture should emit **4 GLYPH_UNMAPPED diagnostics** (one per unmapped glyph):
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1. `GLYPH_UNMAPPED` for glyph `/g001` at code 0x00
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2. `GLYPH_UNMAPPED` for glyph `/CustomA` at code 0x01
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3. `GLYPH_UNMAPPED` for glyph `/glyph_0041` at code 0x63
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4. `GLYPH_UNMAPPED` for glyph `/NotAGlyph` at code 0x64
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### Why These Particular Glyphs
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1. **Coverage:** They represent 4 distinct unmapped glyph categories from bf-1cvmt research
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2. **Test value:** Each fails all 4 mapping levels for a different reason
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- `/g001`: Arbitrary PUA naming
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- `/CustomA`: Custom encoding fabrication
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- `/glyph_0041`: Looks algorithmic but uses wrong prefix
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- `/NotAGlyph`: Orphaned name reference
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3. **Comparison:** Mapped glyphs `/space`, `/A`, `/B` provide baseline for Level 2 (AGL) success
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4. **Fixture simplicity:** All glyphs fit in single-byte encoding (0-255 range)
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## Next Steps
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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.
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## References
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- Research notes: notes/bf-1cvmt.md
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- Font resolver: crates/pdftract-core/src/font/resolver.rs (lines 285-376)
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- AGL lookup: crates/pdftract-core/src/font/agl.rs
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- Diagnostics: crates/pdftract-core/src/diagnostics.rs (lines 569-576)
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- Example fixture: tests/fixtures/encoding/no-mapping.pdf
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