PSS — usage of user defined catalogs unclear.

To my mind the usage and mapping of user defined catalogs is weakly
specified. It is not clearly described what is generated and what has to be
implemented by user. Furthermore it is unclear, how to get access to an
catalog. Subsequently I consider C++ only. I guess, a new implementation
class has to be defined for each catalog, inheriting from the mapped class
of that catalog and from Session. This is necessary to use the operation
create_basic_session() returning a Session. Further I guess, the parameter
catalog_type_name of this operation denotes a catalog supported by a prior
registered user implemented session factory.
Furthermore chapter 6.2 does not sufficiently explain the parameter
storage_home_id of operation find_storage_home() from CatalogBase. In
particular the sentence "In the case of type-specific catalogs (declared in
PSDL), the provide declarations define valid storage_home_id parameters."
allows multiple interpretations. What is meant?

accepted