I have gone through and updated all existing EIPs to match this rule, including EIP-1.
In some cases, people were using markdown citations, I suspect because the long-form was a bit verbose to inline. Since the relative path is quite short, I moved these to inline but I wouldn't be opposed to putting them back to citation format if that is desired by the authors.
In doing the migration/cleanup, I found some EIP references to EIPs that don't actually exist. In these cases I tried to excise the reference from the EIP as best I could.
It is worth noting that the Readme actually already had this rule, it just wasn't expressed properly in EIP-1 and the "Citation Format" section of the readme I think caused people a bit of confusion (when citing externally, you should use the citation format).
* EIP-1: make category field in EIP more clear
* Better heading in README
* EIP-2: fix typo in rendering
* EIP-1: clarify that an EIP can move from the Abandoned status to the Draft status
Also clarify that EIPs cannot move from the Rejected and Superseded states.
* EIP-1: rename WIP status to Idea
* EIP-1: change template formatting to fix markdown rendering
With angle brackets markdown renders them as HTML tags sometimes (depending on the rendering engine).
* EIP-1812: change copyright link to the correct CC0 link