A d2j file extension is related to the d2jsp script files. Probably obsolete.
D2J file extension - d2jsp script
What is d2j file? How to open d2j files?
File type specification:
The d2j file extension is associated with the d2jsp website for some sort of scripts.
Most likely some old format without support from developer. No further information could be found.
This d2j 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.