What is the VFP equivalent for the following VB code?

3partyDll.dll (the dll file)

Signal in 3PartyDll
arguments type
---------------------------
"com1" string
"myfile.txt" string
ExNresult integer && returned - expected Numeric result
ExCresult string && returned - expected Nharacter result
SupError boolean
"" string
mDos boolean

----VB code ----
Dim ExResult as String
Dim Result as Intreger
Dim mDos as Boolean
Dim SupError as Boolean
mDos = False
SupError = False
Call Signal("com1","\MyAppl\Invoice.in",Result ,Exresult, UseDos, "",SupError)

----VFP code ---
DECLARE Signal IN 3PartyDll (how do I pass boolean parameters?)

Thanks