{Note: I haven't yet written a real version of this document. What follows is a cursory description for until I do.
Description
The jcompose.tcl library consists of four procedures which support the Compose key in applications which use the jstools libraries. The procedures in jcompose.tcl are actually buried under a few levels of abstraction, and you shouldn't need to worry about them at all in your applications if you use the j:jstools_init procedure (in jinit.tcl), or if you use j:eb:init or j:tb:init; the bindings set up by those procedures will call the appropriate jcompose.tcl procedures for you.
The procedures are
j:tc:start_sequence - start a Compose key sequence in a text widget
j:tc:finish_sequence - finish a Compose key sequence in a text widget
j:ec:start_sequence - start a Compose key sequence in an entry widget
j:ec:finish_sequence - finish a Compose key sequence in an entry widget
The table of Compose¡key combinations is brought in the first time it's used, via the j:compose_init:iso8859-1 procedure in jlatin1.tcl.
As this implies, jcompose.tcl currently only supports the Latin 1 (ISO 8859-1) character set, which supports languages of Western Europe and the Americas (among others); I hope to support other character sets in the future.