The expressions in SpecList are all of the form name/arity.
Note that unskipped/1 is superseded by the predicate set_flag(Proc, skip, off), which sets the procedure Proc to be unskipped.
Success:
      [eclipse]: [user], skipped p/0.
       q.
       p :- q.
       user compiled 60 bytes in 0.00 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
      yes.
      [eclipse]: unskipped p/0.
      yes.
      [eclipse]: p.
        (1) 0  CALL   p (dbg)?- creep
        (2) 1  CALL   q (dbg)?- creep
        (2) 1  EXIT   q (dbg)?- creep
        (1) 0  EXIT   p (dbg)?- creep
      yes.
Error:
      unskipped Proc/1.           (Error 4).
      unskipped write(Term)/1.    (Error 5).
      unskipped do.               (Error 5).
      unskipped n/1.              (Error 60).