COBOL PROGRAMMING
1) Introduction Cobol

• In 1959, the new language named COBOL (COmmon Business Oriented Language) was introduced keeping in mind the business purpose applications. 
• The first COBOL compiler became available in early 1962. 
• The next version with some new additions was published in 1965. 
• In August 1968 a standard version of the language was approved by the American National Standard Institute (ANSI). 
• This standard version was again modified in 1974 and is known as ANSI-74 COBOL or COBOL -74. 
• The revision process has been continuous and in 1985 a revised standard was introduced. This standard was known as COBOL-85.

2) FORMAT FOR COBOL PROGRAMS 

• COBOL is a high-level language. 
• Hence, a COBOL program can be executed on a computer for which a COBOL compiler is available.
• The compiler translates a COBOL source program into the machine language object program. 
• This object program is really executed. 
• COBOL programs are written in coding sheets. 

• There are 80 columns in a line of the coding sheet. 
• The page number is coded in columns 1-3 and the line numbers are coded in columns 4-6. 
• The page and line numbers together is called the sequence number. 
• Depending on the type, the entries are coded both from column 8 or column 12 and in both cases it can be continued up to column 72. 
• Columns 73-80 can be used to write some identification. 
• The compiler ignores anything that is given in columns 73-80 except when a printed copy of the program is provided by the compiler in which case the entries in columns 73-80 are also listed. 
• The use of the sequence number is also optional and can be omitted. 
• However, when sequence numbers are provided they must appear in ascending order. 

• In COBOL there are two types of entries known as margin A and margin B entries. 
• Margin A entries start from column 8, 9, 10 or 11 and margin B entries start from column 12 or anywhere after 12. 
• An asterisk (*) in column 7 indicates a comment line and the entry is not compiled to produce object code. 
• Comment lines are actually some notes revealing the intentions of the programmer. 
• Since the compiler ignores them, anything can be included as comments. 
• Comment lines can appear anywhere after the first line of the COBOL program. 
• A comment line can also be indicated by using the character slash ( / ) in column 7. 
• But in this case the comment line will be printed after causing a page ejection (i.e., after skipping to the top of the next page).