Whats-New-GPML2021.html Updates Annotations and Citations

[DeniseSl22]

Questions:

• Why is there a URL and Xref? And are both optional, or just one of the two?

[DeniseSl22]

Same question for point 2:

[mkutmon]

1. Annotations: I think for annotations we need to provide some flexibility (example states), so I suggest that only name and type are required - adding more details is obviously encouraged.
2. Citation: We should make URLs required since we can create URLs from Xrefs and add them but sometimes you might just want to refer to a website.
3. Evidence: Xref is required for evidences.