It’s part of uconv’s transform rule syntax: >Each transform rule consists of two colons followed by a transform name. http://userguide.icu-project.org/transfo

It’s part of uconv’s transform rule syntax: >Each transform rule consists of two colons followed by a transform name. http://userguide.icu-project.org/transforms/general#TOC-Compound-IDs http://userguide.icu-project.org/transforms/general#TOC-Comp...