They are just prefixed given to the names and don't have any special purpose other than organising the names.
tm- is a prefix on messages used. I am not certain but I always assumed that it means tiddlywiki message. tc- is used to prefix css class names, presumably standing for tiddlywiki class. -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. To unsubscribe from this group and stop receiving emails from it, send an email to tiddlywiki+unsubscr...@googlegroups.com. To post to this group, send email to firstname.lastname@example.org. Visit this group at https://groups.google.com/group/tiddlywiki. To view this discussion on the web visit https://groups.google.com/d/msgid/tiddlywiki/b9972329-a5b3-4435-b139-8ef02414a2b5%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.