The code that writes this is PrintTOCSummary() in src/bin/pg_dump/pg_backup_archiver.c -- see that if you want more details. (Each object here is a TocEntry struct, which is defined in pg_backup_archiver.h, search for _tocEntry. Useful comments there.)
11471 is the internal ID of the object in the dump. Note that ; is a comment delimiter for the TOC format, so if you just write the 11471 in a separate line, the correct object is specified. The rest of the entries after the ; are just commentary so that the DBA can understand what the entry is for.
1262 is the OID of the pg_database catalog, so this identifies the entry as a database. This is redundant with having DATABASE in the object type. Similarly, 36497111 is the pg_database.oid column which is redundant with having mydb as the database name.
The hyphen - is for the schema, if the object belongs into a schema. A database obviously doesn't have one, hence the - in this particular sample. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services