u-uid

 u-uid  is a microformats2 property for representing a unique identifier for the item, e.g. an unchanging permalink, like a u-url but without any user-authored parts like a slug.

Why
Publishing a stable u-uid for a post will help with implementing updated and especially deleted posts, where the u-url itself may (should in the delete case) change due to an altered (or removed) slug.

Brainstorming
undefined I think a good way to implement u-uid on posts is to specify them as the post permalink but without anything user-authored, or user-alterable e.g. the slug should NOT be part of the u-uid. See URL design for more. I'm planning on implementing this soon. Tantek 10:38, 27 May 2016 (PDT)

Note that if the UID is an opaque string (e.g. a uuid4) rather than a resolvable URI, it should be specified as  instead. Beesbuzz.biz (talk) 20:05, 14 May 2021 (PDT)