[eclipse-users] profiling constraint code

I'm building a planner in eclipse using the constraint libraries.  
It's running rather slow, so I profiled it and got:

                 PROFILING STATISTICS
                 --------------------

Goal:             difficult_testA(MP, [5])
Total user time:  168.30s

Predicate             Module        %Time   Time   %Cum
--------------------------------------------------------
?                     ?             53.5%  89.99s  53.5%
dummy_prop_ic_con /1  ic_constrain  25.2%  42.45s  78.7%
unify_ic          /3  ic_kernel      6.0%  10.13s  84.7%
set_up_ic_con     /3  ic_constrain   5.6%   9.48s  90.3%
ic_exclude        /2  ic_kernel      1.4%   2.30s  91.7%
...

What does that ? ? line mean?
What does 'dummy_prop_ic_con' do?

Are there any tips on how to write more efficient constraint systems?

Malcolm

--
       "An inconvenience is only an adventure wrongly considered;
        an adventure is an inconvenience rightly considered."
                 - G.K.Chesterton, On Running After Ones Hat