The procedures are all of the form name/arity, or else of the form name, in which case all procedures with name name are skipped.
Note that skipped/1 is superseded by the predicate call set_flag(Proc, skip, on), which declares the procedure Proc as skipped.
Success:
      [eclipse]: [user], skipped p/0.
       q.   p :- q.
       user compiled 60 bytes in 0.02 seconds
      yes.
      [eclipse]: trace.
      Debugger switched on - creep mode
      yes.
      [eclipse]: p.
      S (1) 0  CALL   p (dbg)?- creep
      S (1) 0  EXIT   p (dbg)?- creep  % information on
      yes.                             % q not printed.
Error:
      skipped Proc/1.           (Error 4).
      skipped write(Term)/1.    (Error 5).
      skipped do.               (Error 5).
      skipped n/1.              (Error 60).