For academic writing, it would be great to easily refers to papers on preprint servers (such as arxiv) or published (using DOI). When writing notes on projects, there can be a lot of citations, so having shortcuts would be very useful to reduce typing and avoiding cluttering the markdown source.
For preprint servers, the simplest solution would be to create automatically a link when recognizing the server name followed by a preprint ID, for example: arxiv:hep-th/9206084. This is the customary way of sharing papers in theoretical physics for example (so copying information from an email would directly create all necessary links). One could even remove
arxiv: in the preview. A DOI can be linked using the prefix
doi: and the address
More generally, users could provide pairs of name and URL, such that
name:ID maps to