Intel® Fortran Compiler XE 13.1 User and Reference Guides
The following are extensions to the methods and rules for source forms:
Tab-formatting as a method to code lines
The letter D as a debugging statement indicator in column 1 of fixed or tab source form
An optional statement field width of 132 columns for fixed or tab source form
An optional sequence number field for fixed source form
Up to 511 continuation lines in a source program