RK format is a family of proprietary compressed archive formats developed by Malcolm Taylor and RK Software (later M Software). It is the native format of the software named RK (or RK high performance archiver, or RK Archiver), and of the later WinRK. It is a continuation of the family of formats used by RKIVE, the predecessor of RK Archiver.
WinRK is a full-featured archiving application that supports several standard formats, as well as its native RK format. The RK format version used by WinRK is sometimes called WinRK archive (e.g. by WinRK v1.1.3, to distinguish it from RK v1.04.1 format).
This has no connection to a different WinRK, which appears to be a UK-based database used for record-keeping by bell-ringers.
There are at least 5 significantly different archive file formats in the RKIVE/RK/WinRK series:
- RKIVE 1.0-1.1 (see RKIVE for the "RKIVE" formats)
- RKIVE 1.2-1.4
- RKIVE 1.92beta1 (Don't know if there are any other 1.9x versions.)
- RK Archiver 1.4.1alpha (There are earlier versions of RK Archiver; don't know what format they use.)
- WinRK (All versions? At least v1.1.3 to v3.1.2.)
Even within one of these classes, different versions are not necessarily compatible.
(This assumes the format is not RKIVE v1.92beta1 -- read RKIVE#Identification first.)
RK/WinRK archives end with a 2-byte signature: ASCII "
RK". The three bytes preceding this signature contain version information, though for WinRK it's really just dummy information. The major version number is the low 6 bits of the 5th byte from the end of the file. It is 1 for RK Archiver, 2 for WinRK.
WinRK archives are observed to start with these 13 bytes:
aa 04 00 00 00 00 ad bb da 04 00 00 00. They end with
02 00 00 'R' 'K'.
RK Archiver format has no header at the beginning of the file. The v1.4.1alpha version info bytes are
0x81 0x04 0x01. But there are earlier versions of RK Archiver which, even assuming they use this format variant, would have different version numbers.
- RK v1.04.1 alpha for DOS
- RK v1.04.1 alpha for Windows (console)
- WinRK v1.1.3 (Windows GUI)
- WinRK v3.1.2 (32-bit) (Windows GUI)
- WinRK v3.1.2 (64-bit) (Windows GUI)
- RK Software downloads page (from archive.org)
- RK Software (last Wayback Machine capture, 2004-12-16)
- M Software website (2016 archive)
- For a list of RK format features, see winrk312.exe (NSIS format) → WinRK.chm, §1.1.1 "Features".