What does a schema name and catalog name in hibernate mapping file mean?

I am using sybase and I have multiple dbs in the same database server. We have only one datasource configured and till now we were accessing the other db using dbname..tablename convention. I am trying to find an equivalent mapping in hibernate. Tried both schema and catalog in hibernate-mapping element but both were generating dbname.tablename ( instead of dbname..tablename )
Any suggestions ( other than configuring a different datasource :) )

Thanks

i am not clear with catalog.

In the Mysql, postgres or mainframes there are different schemas will be there. that is called as dbs.