FORTRAN Function Redeclaring Array

So I have this code for a FORTRAN fuunction and I am curious what is happening to the parameter X?

DOUBLE PRECISION FUNCTION PBOIL(NGamma,T,X)
IMPLICIT DOUBLE PRECISION(A-H,O-Z)
DIMENSION X(NGamma),GAMMA(NGamma)

Is X an array when it's passed in? Is the X that is declared in the 3rd line different than the parameter X? Thanks.