The main documentation of the MaxVal_Real_Scalar Procedure contains additional explanation of this code listing.
function MaxVal_Real_Scalar (R) ! Input variable. type(real), intent(in) :: R ! Output variable. type(real) :: MaxVal_Real_Scalar !~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ! MaxVal_Real_Scalar is equal to R. MaxVal_Real_Scalar = R return end function MaxVal_Real_Scalar