Question: Recursive call of a proc

I am having difficulties with a recursive function call with named parameters.

The proc is defind as follows:

Subs:=proc(eqn::seq(equation),elemt::Element,{num::boolean:=false},$) option remember;
...
qs[i]=Subs(eqn,elemt[qs[i]]); # This is where I need to add something like 'num'=num
...
end proc;

My difficulty is with the "num" flag. In the code this flag governs whether to try to evalf() certain results or not. That and the recursion per se all works. What does not work is when I add the num option to the internal call. I have been trying 'num'=num, ''num''=num, "num"=num and `num`=num.  I either get an error that something like true=true is not a valid argument here, or that "num" is not valid.

Any hint?

Thanks,

Mac Dude