yes, seems like they are sorted by tag. But that’s not useful, since you cannot use numbers in a tag. This tag is just the workaround for abbreviations that include numbers.
\abbreviation[0123]{123}{One, Two, and Three}
\abbreviation{ABC}{A, B, and C}
\abbreviation{ZYX}{Z, Y, and X}
\starttext
\csname 0123\endcsname
\completelistofabbreviations[criterium=all]
\stoptext
--
luigi