Frame types - range for custom IDs

Hello ,

I would like to know which range for Frame types can be used for custom frames( would like to build own app protocol)

I went through all documentd available for Decawave modules and boards. And I underdtand there are IDs for blink, poll, rx … messages.

Which range is reserved for custom Frames?

Could you please point to a document I might not have seen or answer here.

Many thanks.