AT Protocol: shared lexicons for publishing and indexing

Standard.site proposes shared lexicons for publishing platforms on AT Protocol. The goal is to give indexers and tools a common schema while making content easier to discover and move between hosts.

The standard describes metadata for publications, documents, and subscriptions without prescribing a content format. Each platform can choose which lexicons to implement. Verification uses a /.well-known/site.standard.publication route to link a domain to its publication, and an HTML tag to associate a document with its AT-URI.