Each input and output
name is a unique property. Inputs expect a value
to be assigned to the property upon a call to the service. Outputs assign a value to
properties. Efects and Preconditions are Conditions.
Conditions consist of a fluent together with a set of
properties, each of which may or may not have a bound value
for any one or all states in which the service is called:
e.g., (Transfered (amount $500) (from-account 8238) (to-account 2834))