Suggestions for future language support

[rly]

1. Allow a user to specify that, for example:

   • One of TimeSeries.timestamps or TimeSeries.starting_time is present, but not both
   • If one of control and control_description is present, both must be present.

   Such functionality is supported in JSON Schema and LinkML. The cost of adding support for this is currently high, given other priorities, but if/when we migrate to using a different language such as LinkML, we should update the nwb core and hdmf common schema to make use of these.

2. Datetimes without time zone (see discussion in allow datetimes to be just dates NeurodataWithoutBorders/nwb-schema#542)

3. A union of types, e.g., date or datetime. Float or int.