TSFL_Fields == DOMAIN TSFL_Domains
InTSFL(x) ==
/\ DOMAIN x = TSFL_Fields
/\ \A f \in TSFL_Fields :
x[f] \in TSFL_Domains[f]
If you can write your spec using InTSFL rather than TSFL, then this
will solve your problem. Otherwise, you will not be able to use TLC
to check the spec.
Leslie