Hi everyone. We (MobilityData) want to get some thoughts from the community on updating GTFS to RFC 2119.

In short, RFC 2119 is a standard of keywords to indicate requirement levels (i.e., "MUST", "SHOULD"). It is used by similar data standards such as GBFS and IMDF to draw clear distinctions around what is required and what is recommended in the specification. These clear distinctions are not made in GTFS, leaving room for interpretation, ambiguity, and make the spec harder to grasp for both newcomers and experienced stakeholders when it comes to producing, consuming, and creating products (i.e., validators) around GTFS.

In terms of updating GTFS documentation to RFC 2119, little change would be needed in the majority of cases. In some cases, parts of the spec may need minor edits to be RFC 2119 friendly, without changing the content (such as replacing "can" with the RFC "MAY"). The goal is to have a data standard that is legible and clear.

Pending feedback here, we would begin this work with GTFS Schedule, followed by GTFS Realtime. Looking forward to any thoughts on this. Thanks!