There are many different API gateway products available, both open source and proprietary. They will often include elements for a dev portal and/or a catalogue. You can read more about these further in this guidance.
I'm not sure where they are discussed? Or is it things like dev portal/catalogue?
Feedback on 'APIM - 04 - Management' (https://alphagov.github.io/data-standards-authority/guidance/apimanagement/APIM-Management.html)
Emphasis mine:
I'm not sure where they are discussed? Or is it things like dev portal/catalogue?