Detail how "Doc ID with regex" should be used with "Type mapping"

Reading https://docs.couchbase.com/server/6.0/fts/fts-creating-indexes.html#specifying-type-identifiers and https://docs.couchbase.com/server/6.0/fts/fts-creating-indexes.html#specifying-type-mappings

it is still unclear what Type Mapping should be defined in case we previously select Doc ID with regex type identifier.

Answer for Abhi Dangeti from an internal discussion :
you’d need to set the type mapping name to a string that matches docid_regexp

An example (not found here nor in any tutorials/blogs I found on FTS) should be created too (one per case if possible).