Columns 7 through 72

Fortran statements are to be written in columns 7 through 72. There is no need to left-justify the commands. This is where the vast majority of all your Fortran instructions will be placed.

Columns 73 through 80

These lines will not be used by Fortran and can be used to number the lines of the source code or for other purposes. Historically, the punch cards were labelled in these columns so that if you dropped a stack of the cards, then you would be able to easily reorder them.

On the next page you will see Example 1 written in Fortran 77.