The data contained on Inputs Version 0.1.1 - Interoperability Data for the Fediverse describes what is currently allowed by the various microblogging applications in the Fediverse. One could now extract from it a document describing the allowed datastructure
inReplyTomust be a single elementid,attributedTo,content, andpublishedshould be present
And more questionable ones, tainted by where I want the Fediverse to go,
url,attachment, andtagcan be lists containing blank nodesreplies,likes,shares,contextcan be a single element (like inReplyTo`)
Question: Would this be what people here call a microblogging profile? Or are people imaging something different under this term?