ASL @glyf

Notes on the new ASL @glyf tag as of 2025-04-02 [not fully implemented]

Purpose

@glyf supports non-contrastive variant (proto-)cuneiform glyphs for @sign and provides a place to define an ATF notation for accessing them, their permanent location in the Oracc PUA, and their accessibility via IVS as well as OpenType Font Features. This gives a machine-readable way of recording in PCSL and OSL glyphs that are not encoded as Unicode characters.

Note that @glyf is intended to support general, persistent recording of only a selected subset of variant glyphs. Many glyph variants will exist beyond the definition of @glyf, accessible through font features in specialized fonts. For Oracc cuneiform fonts, each font has a table giving details on the availability of variants which are otherwise only defined within the fonts themselves.

The primary reasons for selecting variants for recording as @glyfs is their presence in a major sign list (e.g., the CDLI github-repository of Proto-Cuneiform signs) or their function as a significant structural variant of a sign where the structural variant is not deemed appropriate for encoding as a character (e.g., the various avatars of DE₂ as UMUM@s, |UMUM×KASKAL|, |UMUM×PA|).

Only standalone signs can be defined as @glyfs; sequences must use @form. The rationale for this is that @glyf exists as a mechanism to define non-contrastive forms for encoded or encodable characters, and sequences are not generally considered encodable. A further technical reason for this is that in Oracc sign-keys the sign is always the first component and the value is the third and final component. The second component is either a @form OID or a @glyf OID.

Location

@glyf may occur zero or more times in the body of an @sign and this @sign is referred to as the @glyf's parent.

@glyf entries must come at the end of the parent @sign block,

@glyf entries have no corresponding end tag; @glyf is terminated by the next `@glyf', `@form', or `@end sign'.

@glyf entries may include an entry for the reference glyph of a Unicode encoding.

Syntax

@glyf NUM OID UNI PUA OTF

NUM: NUM is an integer unique to the @glyf within the direct child @glyfs of a @sign or @form. By convention, we number from 1. An initial '*' indicates that the @glyf is used as the Unicode reference glyph in an encoding, so @glyf SAG *1 ... would indicate that @glyf 1 of SAG corresponds to the reference glyph.
OID: is the Oracc ID of the @glyf.
UNI: is the Unicode character literal of the following PUA assignment.
PUA: is the permanent location of the @glyf in the Oracc PUA; @glyf PUA assignments start at U+FA000 in the Oracc PUA.
OTF: is zero or more OpenType Features which can be used to access the @glyf. These may be SALT (.[0-9]+); CVNN character variations; or SSET Stylistic set codes. Note that each OFF must begin with a '.' (period); this is part of the syntax of OTFs in @glyfs.

Restrictions

A @glyf-name may not occur within the name of a @sign. In PCSL this means that KUŠU₂~a would be a legal sign or form name, but SAG~v1 would not.

Accessing Glyfs

Reference Images

By definition, any @glyf that is listed in PCSL or OSL is provided with a reference image that is avaiable via the URL:

'/' (pcsl|osl) '/' glyf '/u' PARENT-UNICODE-HEX '_' GLYF_NUM '.png'

Thus, for @glyf 1 of a sign SAG encoded as U+12777 in PCSL the image file would be /pcsl/glyf/u12777_1.png.

ATF Transliteration

The ATF graphetic notation is used to reference @glyf forms in ATF transliteration. Thus, the SAG @glyf in the previous example would be accessed as SAG\1.

Fonts

Oracc cuneiform fonts observe the following rules in implementing @glyfs:

CVNN variants are used, with the CV for each @glyf corresponding to the @glyf NUM, i.e., @glyf SAG 1 from the above examples would be defined in a PCSL font as U12777.cv01.
SALT variants are not used
An SSET collection is defined for Uruk IV, ss04, and that sset is reserved within Oracc for Uruk IV glyphs

Examples

(1)

@sign SAG
@oid o0901677
@list U+12AA9
@ucun 𒪩
@uname SAG
@uage 1
@list ZATU437
@glyf 1 o0901678 󺀀 FA000 .1 .cv01 .ss04
@glyf 2 o0901679 󺀁 FA001 .2 .cv02
@list BAU228
@end sign

Notes on Example (1)

Only @sign has the usual Unicode information; @glyf has only the information in the @glyf entry.
A @glyf may have metadata elements like @list or @sys, but should not have a Unicode `@list U+' entry.