Neither form supplied here appears to be valid, although I could be wrong.
According to Fortran 95/2003 (by Michael Metcalf, John Ker Reid, John Reid, Malcolm Cohen), on pg. 276 it states:
"If the association is with an expression, the associate-name may be used only for its value."
Both forms supplied here result in a compilation error when trying to assign to X:
sample.f90(6): error #6421: This scalar or array name is invalid in this context.
x = x / 5d0
----^
If you modify the use to assign to a variable other than X, each form is accepted and executes as expected.
