While we used to have PAD files for our software in the past, the Association of Software Professionals (formerly Association of Shareware Professionals), aka "ASP" has, some years back, ruined this for everyone by trying to force a walled-garden registry upon the use of it. First off, they trademarked PAD, so it's now PAD®, and then they enforced everyone to use the latest version of the specification, v4.0, which is exclusively registry bound in AppVisor, through their ownership (key statements highlighted):
(Source: http://appvisor.com/pad/pad-faq/)Q: Who owns PAD and who can use it?
A: The ASP has ownership of the PAD Specification format. This includes the copyright for intellectual property format, the trademark for PAD (certified mark) and other marks. Any publisher that uses a PAD file is given a free license to use the PAD Specification, as long as the publisher commits to using the latest specification version, validation, and authoring tools. The ASP also owns the certified trademark of the PAD Specification and requires all third party sites and service providers who base their products or services on PAD files to sign a license giving them permission. Contact the ASP’s PAD Chair here:http://pad.asp–software.org for further information.
This means that using older version PAD files to base your service around (either as a software publisher or software portal publisher) is prohibited. Any portals should be warned that continuing to use PAD spec 3.11 or derived formats makes them subject to potential legal claims for trademark violation.
So there you have it -- this is why we can no longer use PAD files for Pale Moon, and why nobody in the software distribution market should still be using them.