From the introduction:
The following Home World and Career Mementos are an optional component you can use during Character Generation and adds a further degree of colour to your Acolyte's background and personality. In addition, GMs may wish to use these items to embellish Non Player Character descriptions.
Additional User Summary:
The document includes tables of random trinkets by both Home World and Career Path. Only the core Home Worlds (Feral World, Hive World, Imperial World, Void Born) and Career Paths (Adept, Arbitrator, Assassin, Cleric, Guardsman, Psyker, Scum, Tech-Priest) included in the Dark Heresy core rules are covered.