FOAF:

   * aimChatID
   * based_near
   * birthday
   * family_name
   * firstName
   * gender
   * homepage
   * icqChatID
   * maker
   * mbox
   * msnChatID
   * nick
   * phone
   * yahooChatID

SIOC:

   * has_container
   * has_creator
   * id
   * link
   * topic

vcard:

   * ADR
   * BDAY
   * CATEGORIES
   * EMAIL
   * FN
   * N
   * NICKNAME
   * UID

PREFIX sioc: <http://rdfs.org/sioc/ns#>
PREFIX sioct: <http://rdfs.org/sioc/types#>
SELECT DISTINCT ?attribute
WHERE
  {
    ?forum a sioct:AddressBook .
    ?forum sioc:container_of ?post .
    ?post ?attribute ?o  
  }

Sample Data (Live Query Results)

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