How to indicate ARR deadlines

Right now the yaml format assumes conferences with locations and dates, but ACL ARR has rolling deadlines not tied to a physical conference. We are largely operating around these deadlines. How can we incorporate these into this system?

Start by reviewing how the YAML format represents conference locations and dates, and where those values are consumed; no file or test is named in the issue. Define how rolling ACL ARR deadlines should be represented and what behavior should confirm that the new format works without a physical conference.

Written by the indexing model from the issue text.