Windows 3.x/3.1.61

This build is mentioned in Microsoft antitrust document PX01168 from January 1992, along with 58 and 60.

The document reveals that the build was thoroughly tested and passed most of the tests.

It is also mentioned in document PX01251 alongside builds 71, 101 and RCs 1-3, as well as TERMINAL.EXE in early Chicago builds.