6.4 Gaiji (外字)

Synopsis

A gaiji (外字, "external character") is a glyph outside the assumed character repertoire — a rare kanji, a special kana, a symbol. It is written as a ※［＃…］ reference carrying a human description and, where possible, a machine address (a JIS X 0213 men-ku-ten or a Unicode code point) that resolves it to an actual character.

Notation

gaiji-ref = REFMARK directive          ; ※［＃ description 〔、address〕 ］

※［＃「てへん＋劣」、第3水準1-84-77］     ← JIS X 0213 men-ku-ten
※［＃「口＋世」、U+546D、123-4］          ← Unicode reference (+ provenance)
※［＃「土へん＋竒」、123-4］              ← description only (provenance locator)
※［＃二の字点、1-2-22］                  ← named, with men-ku-ten
※［＃二重かっこ開く］                    ← named, dictionary-resolved (no address)

A description in 「…」 quotes is recognised on its own; a bare (unquoted) description with no address is recognised only when it names a known dictionary glyph (※［＃二重かっこ開く］ → ｟, the same glyph as the upstream 始め二重括弧 entry), so an ordinary ［＃…］ directive is not mistaken for a gaiji. The canonical serialization quotes the description (※［＃「二重かっこ開く」］). Vector: gaiji_double_paren.

A bare ローマ数字N description (※［＃ローマ数字17］) is recognised the same way, with the glyph composed rather than looked up: the numeral N is spelled from the U+2160 (uppercase) / U+2170 (lowercase, ローマ数字N小文字) single-letter Roman-numeral blocks — 17 → ⅩⅤⅠⅠ (Ⅹ+Ⅴ+Ⅰ+Ⅰ) — because values ≥ 13 have no single JIS X 0213 cell (the corpus pairs those with a page-line locator, not an address). It resolves like any other gaiji and serialises to the canonical quoted form (※［＃「ローマ数字17」］). Vector: roman_numeral.

The accent form 〔…〕 (§4.3, Annex A) and the iteration marks ／＼ / ／″＼ are related glyph-encoding notations covered in Annex B.

Standalone form (tolerant)

Some 凡例 write the same ［＃description〔、address〕］ reference without the leading ※ — a standalone descriptive note rather than an inline insertion. A conforming processor SHOULD recognise it as a gaiji node when the body carries a resolvable description or a mencode / page-line address (so an ordinary ［＃…］ note is not mistaken for one), and serialise it back without a ※. This is a corpus-attested tolerant extension, not part of the core external_character.html notation; the reference-mark form above is canonical. Vector: standalone_gaiji.

Parameters

• description — the text before the first 、: a radical composition (木＋世), a name (二の字点), or a directly-typed character.
• address — an optional 、-separated trailer: a JIS X 0213 men-ku-ten (第N水準P-R-C / 面-区-点), a U+XXXX code point, and/or a page-line provenance locator.

Semantics

• The reference yields a gaiji node whose span covers the whole ※［＃…］. Resolution order is normative (Annex B): explicit U+XXXX, then men-ku-ten, then a named description (including the composed ローマ数字N numerals), then a single-character description.
• On success the node carries the resolved scalar (or combining sequence); reference rendering (§8) emits that character (optionally wrapped for styling).
• Serialization reconstructs the ※［＃…］ reference byte-exact (§7.6); a resolved gaiji round-trips to its source form, never to the bare glyph.

Error conditions

• Unresolved — a reference that resolves to neither Unicode nor JIS X 0213 raises unresolved-gaiji (warning) and falls back to the description text.

Conformance vectors

gaiji, gaiji_double_paren, roman_numeral, unresolved-gaiji, accent-decomposition-applied.