Actual parameters

Observe how ActualParameterSequence is defined by

ActualParameterSequence	$\longmapsto$	ActualParameter
ActualParameterSequence	$\longmapsto$	$\varepsilon$
ActualParameterSequence	$\longmapsto$	ActualParameter , MoreParamters
MoreParamters	$\longmapsto$	ActualParameter
MoreParamters	$\longmapsto$	ActualParameter , MoreParamters
ActualParameter	$\longmapsto$	ArithmeticExpression

In particular, an actual parameter cannot be a function call. This is meant to simplify type checking. Of course, this restriction can be worked out by the programmer by using temporary variables.