Permitted attachment types

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I was about to post a HPGCC3 program in the software library when the forum hit me with the message that my attachment type was not allowed. The extension was HPGCC3's default .ex3.
When I tried my backup plan, which involved changing its extension to the ConnKit's preferred extension .hp, I got the same message.
Of course I could compress the file, but a ZIP archive containing a single 15KiB file is neither convenient nor particularly memory-saving.
Could these attachment types be allowed? Preferably together with other common file types for HP calculator software, e.g. .hpprgm for Prime programs.