Format Registry documentation is not accurate / well published
Looking on the page here https://spec.openapis.org/registry/format/ as well on the JSON content here https://spec.openapis.org/api/format.json
there are some mistakes in the collumn type
for instance : decimal A fixed point decimal number of unspecified precision and range stringnumber should be string, number
for in64 we have an other version int64 signed 64-bit integer numberstring
only sf integer looks correct
then about the JSON content , to me the given the constrains that a format can apply to multiple base type it should be represented as an array
"base_type": "numberstring" => "base_type": [ "number","string"]
Looking a bit deeper in gh-page repo , it looks like data is accurate , but it is more a generation issue of the HTML document and of the JSON document that does not leverage the data
for instance int64 is correctly described here https://raw.githubusercontent.com/OAI/OpenAPI-Specification/gh-pages/registries/_format/int64.md
Yes, something is concatenating two type values instead of rendering them as a comma-separated list.
I found a solution on this one and I will open a PR soon. It is worth noting that the only reason the sf-integer is shown correctly it is because we have wrongly set its base type to string. Which means that the base type is basically set to "integer, string" instead of ["integer", "string"].
You can check it also by the produced JSON: https://spec.openapis.org/api/format.json
Resolved by @Bellangelo 's PR - I just checked the rendered pages and they look good now.