.3D6 File

It is, under RISC OS, a "StrongHelp file" which is an image consisting of a number of data files (RISC OS's hooks make doing this sort of thing possible - a single "file" becomes a virtual filing system that contains files). Anyway, StrongHelp was designed to provide marked-up online help in the days before anybody knew what HTML meant.

This 3d6 file type entry was marked as obsolete and no longer supported file format.

This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.

How to open:

Use compatible tools to work with *.3d6 files.

How to convert:

Probably cannot be converted to other formats.