This is a add-on for Windows 3.1. Windows for Workgroups 3.11 (originally codenamed Snowball) was released in December 1993. It supported 32-bit file access, full 32-bit network redirectors, and the VCACHE.386 file cache, shared between them. The standard execution mode of the Windows kernel was discontinued in Windows for Workgroups 3.11.
A Winsock package was required to support TCP/IP networking in Windows 3.x. Usually third-party packages were used, but in August 1994 Microsoft released an add-on package (codenamed Wolverine) which provided limited TCP/IP support in Windows for Workgroups 3.11.
Limited compatibility with the (then-new) 32-bit Windows API used by Windows NT was provided by another add-on package, Win32s. There was a rumor that Microsoft didn't want to increment any mainstream Windows 3.1x version to something like "Windows 3.2" because it could be scrambled with the Win32 API or otherwise distract consumers from upgrading to some 'real 32-bit OS' like the then-upcoming Windows 95 was. In fact, only for the limited Chinese market did Microsoft release a true Windows 3.2 version (see Windows 3.2 section).
Windows 3.x was eventually superseded by Windows 95 and later versions which integrated the MS-DOS and Windows components into a single product.