h-x-app is a proposed microformats vocabulary for marking up data about software applications.
There's a bunch of research into existing formats and potential properties over on store. See below for current, experimental usage.
IndieWebCamp Creators publishing h-x-app markup
h-x-app markup with name, logo/photo and url properties on waterpigs.co.uk via Taproot, also marked up as h-product, to provide basic information about the Note Posting UI to authorization UIs.
Aaron also added
h-x-app markup to the IndieWebCamp wiki with name, logo/photo and url properties.
<div class="jumbotron h-x-app"> <h1> <img src="/images/quill-logo-144.png" class="u-logo p-name" alt="Quill"> Quill </h1> </div>