Currently, CSL assumes that
citation-label is provided as flat text by the supplying client. For
label citation styles, styles differ regarding their preferred citation label, however (e.g., see https://forums.zotero.org/discussion/80232/citation-label-trying-to-prepare-iste-stylesheet#latest). The main differences are whether to use 3 or 4 letters to define the label, whether to include a year, and how to handle disambiguation and items without authors.
Currently, citeproc-js has a hardcoded pattern:
Aaaa00:AaAa00:AaAA00:AAAA00. Jursim has a preference to customize this pattern. Other clients could add similar preferences, but this seems like something that may best be handled by CSL rather than an ad-hoc solution determined by clients.
There was this discussion a while back when citeproc-js added its default format, but that discussion seemed to assume that
citation-label referred to a BibTeX key, not a rendered citation label ala DIN 1505-2 or similar styles.
If this isn’t something we want to define in CSL, it seems like at least the processors might want to include a hook for generating or supplying
citation-label, in the same way that citeproc-js does. @cormacrelf