HP Fortran Programmer Guide HP-UX 11i v1, HP-UX 11i v2, and HP-UX 11i v3 (B3908-90032,December 2012)

NOTE: Using this directive to incorrectly assert that a routine has no side effects can result in
wrong answers when a call to the routine is embedded in a loop.
Cray's implementation of this directive requires that it precede any executable statement or statement
function. HP Fortran does not enforce this requirement.
128 Using Fortran directives