Class Precedence List:
SYMBOL-TEMPLATE, TYPE-TEMPLATE, TEMPLATE, STANDARD-OBJECT, T.
The SYMBOL-TEMPLATE class is the class of the objects that UNIFY recognizes as symbol templates.
The specification of a SYMBOL-TEMPLATE has one of the two forms below:
#T(symbol <value>)where value must be either a unification variable or a SYMBOL.
Unifying a SYMBOL-TEMPLATE against a non-SYMBOL object results in an UNIFICATION-FAILURE error being signaled.
NIL-TEMPLATE should be used to specifically UNIFY against NIL.