Abbreviations like 't', 'm', 'zt', 'sf' in chess databases I am just cleaning up the Event and Site headers in the games in my chess database.
There are a lot of abbreviations there. I am relatively sure about the following:

of, qf, sf and f – octo final, quarter final, semi final and final.
zt and izt  – zonal tournament and interzonal tournament.

But I could need help with these:

tt – Transnational Tournament? Training Tournament?
m (also: mt) – Masters? Match? Men? Memorial?
Tch – Transnational Championship?
It – Invitational Tournament? Italia?

Any hints are appreciated.
Wikipedia says TT is Transposition Table...
When the search encounters a transposition, it is beneficial to 'remember' what was determined last time the position was examined, rather than redoing the entire search again. For this reason, chess programs have a transposition table, which is a large hash table storing information about positions previously searched, how deeply they were searched, and what we concluded about them. Even if the depth (draft) of the related transposition table entry is not big enough, or does not contain the right bound for a cutoff, a best (or good enough) move from a previous search can improve move ordering, and save search time. This is especially true inside an iterative deepening framework, where one gains valuable table hits from previous iterations.
IT seems to hint at Invitational Tournament, though I cannot confirm this.