Columns 1 through 5

Columns 1 through 5 are used for statement labels (we’ll get into that later). If you insert a c (upper or lower case) in column 1, then the line will be treated as a comment line when you compile the program and it will be ignored when the program is run.

Column 6

Sometimes, you will find that you don’t have enough space to write all the commands that you want on one line within the restrictions imposed in fortran 77. If you place a + or an & in column 6 then this indicates that you wish to continue writing commands from the previous line onto the next line. It is called a continuation.
There is more on the coming page.