"Traditionally, COBOL programs were written on coding forms and then punched on to punch cards. Although nowadays most programs are entered directly into a computer, some COBOL formatting conventions remain that derive from its ancient punch-card history.
On coding forms, the first six character positions are reserved for sequence numbers. The seventh character position is reserved for the continuation character, or for an asterisk that denotes a comment line.
The actual program text starts in column 8. The four positions from 8 to 11 are known as Area A, and positions from 12 to 72 are Area B.
Although many COBOL compilers ignore some of these formatting restrictions, most still retain the distinction between Area A and Area B.
When a COBOL compiler recognizes the two areas, all division names, section names, paragraph names, FD entries and 01 level numbers must start in Area A. All other sentences must start in Area B."
<img src="http://www.csis.ul.ie/cobol/Course/Resources/pics/CodingForm.jpg" alt="Ancient Cobol Coding Form" />
Hope this helps.
Just to complete this issue, columns 73 - 80 (on punch cards) were used to store the name of the program or version number. This was optional, but very useful if you dropped a tray of punched cards containing several programs.