TERSE is a data compression format used on OS/2.
More research is needed to understand the scope of what TERSE was used for, and how many versions of it there are.
It can at least be used for single-file compression, as is done by the Advantis software listed below. This file format does not appear to have a conventional filename extension – compressed files may keep their original name.
At least some TERSE-compressed files start with bytes
05 01 01 00.
The ZIP format documentation (APPNOTE) lists two "TERSE" compression methods:
10 - PKWARE Data Compression Library Imploding (old IBM TERSE) 18 - File is compressed using IBM TERSE (new)
So, apparently, PKWARE DCL Implode is closely related to TERSE.
- TERSE utility by Michael Nagy and Advantis