On 12/12/23 01:49, Jeremy Nicoll wrote:
There's no concept of filetype in file systems used for the MVS side of z/OS systems. (These days there's also Unix/Linux environments & of course they do have more familiar file naming structures.)
If you look at the NTFS file system - supported by most O/S including Debian, the file extension is only of use to user programs to help users select they type of files they want e.g. .jpg. It has no meaning at all to the applcations that use them.
Underneath the hood of a NTFS file is alternate data streams (ADS). That is a single file can contain main different 'sub files' of completely different content type. Each ADS has metadata describing the stream.
ADS were first conceived to provide say different language versions of a text file, but that is only an example. An ADS in a file could contain an executable as well as a text file. Theoretically you could also have a video stream and a subtitle stream and multiple audio streams, but that is usually better provides by container formats like ogg vorbis
In unixland file systems like ZFS have extended attributes but nothing like ADS
