[Xsb-users] Help

[<bo...@ut...>]

I am a student at Univeristy of Toronto, and currently study the prolog by
using the XSB, when I load the DCG, and want to see it in prolog clause 
by typing listing.
I  got nothing except |?- Yes, why it happened, how can I see the prolog
clause of the DCG?

Thank you very much for your help!

Bo