\df PATTERN, what pattern?

The consoled help says that the useage for \df is \df [PATTERN]. What is
the pattern matching on? How does one use the pattern?

I have tried "patterns" (function name, data type, schema name) but none
matched anything ...

Also how does one get a listing of all functions? A \df gives me:

"trigger"                   | public     | pot_documents_duplicate_check
         |
"trigger"                   | public     | pot_hostnames_duplicate_check
         |
"trigger"                   | public     |
pot_operating_systems_duplicate_check |
"trigger"                   | public     | pot_referers_duplicate_check
          |
"trigger"                   | public     |
pot_user_agents_duplicate_check       |


I see all the triggers I have defined but not the functions that those
triggers use or any other functions I have created ...

Thanks,

Jean-Christian Imbeault