Goal templates such as this are used in reference page synopses and elsewhere:
setof(+Template, +*Generator, *Set)
Here Template, Generator, and Set are meta-variables, mnemonic names for the arguments. Preceding each meta-variable is a symbol indicating the mode of the argument: whether it is an input or output, and information about its determinacy. These mode annotations are discussed in detail in mpg-ref-mod.
Please note: The system of mode annotations used in release 3 has not been applied to the Quintus Prolog Library.