This package from freedesktop.org's includes the standard MIME-type XML description files and the update-mime-database command. It is often provided in a Puppy's devx sfs. This provides a standard for MIME-types in Linux. How To Add MIME Type tells you how this works in Puppy.

Install devx sfs or appropriate package:-

How To Add MIME Type
AssociateFiles - How Associate filetypes
Internet Media Types