5 CFR §2421.11

1. (a)Any labor organization, employing agency or activity or individual filing a charge, petition, or request;
2. (b)Any labor organization or agency or activity
   1. (1)Named as
      1. (i)A charged party in a charge,
      2. (ii)A respondent in a complaint, or
      3. (iii)An employing agency or activity or an incumbent labor organization in a petition;
   2. (2)Whose intervention in a proceeding has been permitted or directed by the Authority; or
   3. (3)Who participated as a party
      1. (i)In a matter that was decided by an agency head under 5 U.S.C. 7117, or
      2. (ii)In a matter where the award of an arbitrator was issued; and
3. (c)The General Counsel, or the General Counsel's designated representative, in appropriate proceedings.