Every programming language is designed with some system-defined set of characters, symbols, keywords, and standards. Similarly, COBOL has its own set of characters, symbols, keywords, and standards. Below are the basic and known terms in the COBOL –

• Character set
• Character strings
  • COBOL Words
  • Variables
  • Literals
  • Constants
  • Figurative Constants
  • Comments
• Separators

Character set

The character set refers to the collection of valid characters. They define literals, variables, and other identifiers in a COBOL program.

The COBOL language has its own set of valid characters (78) that contains alphabets (A-Z | a-z), digits (0-9), and special characters. The list of basic COBOL characters is as follows –

Character	Meaning	Character	Meaning
	Space	'	Apostrophe
+	Plus	(	Left parenthesis
-	Minus or hyphen	)	Right parenthesis
*	Asterisk	>	Greater than
/	Forward slash or solidus	<	Less than
=	Equal sign	:	Colon
$	Currency sign	_	Underscore
,	Comma	A - Z	Alphabet (uppercase)
;	Semicolon	a - z	Alphabet (lowercase)
.	Decimal point or period	0 - 9	Numeric characters
"	Quotation mark

Character Strings

The character string is a set of characters created for a purpose or to name something. Character strings creates -

• COBOL Words
• Variables
• Literals
• Constants
• Figurative Constants
• Comments

COBOL Words

A COBOL word is a set of characters, and each character is from the character set - A to Z, 0 to 9, - (hyphen), _ (underscore). COBOL word minimum length is one character and maximum length is 30 characters.

COBOL Word Types -

COBOL words are two types, and those are -

• User-defined Words - These are the words you, as a developer, create to fit your specific needs. They can be anything from MTHPROG1, STD-GENDER, reflecting the unique aspects of your COBOL program. For Example - MTHPROG1, STD-GENDER, ....
• Reserved Words - A reserved word is a system-defined word with proper meaning or task assigned in COBOL language. For Example - ACCEPT, SKIP1, ZEROS, ....

Variable

A Variable is used to store and process the value. It holds a pointer to memory location where actually the value stored. A Variable is also called a data item. For Example - WS-A, WS-VAR, WS-TOTAL, WS-INPUT, WS_OUTPUT, etc. Every variable should be declared in the DATA DIVISION of the COBOL program.

We will discuss more about variables in the further topics.

Literal

The literal is the value that is assigned to the variable. The value can be a string or number. Literals are two types –

• Non-numeric literals - Non-numeric literals are the strings enclosed by quotation marks(") or apostrophes('). It can contain all valid character that are allowed by COBOL.
  For Example - "HELLO", "THIS ISN'T WRONG", etc.
• Numeric literals - A numeric literal is a number that is a combination of a sign (+ or -), and a decimal point. A numeric literal codes directly without quotation marks(" ") and apostrophes(' ').
  For Example - 1234, -1234, etc.

Constant

A variable is initialized with a literal. If the variable value doesn't change during the program's execution, the variable is considered as a constant variable, and the value is considered as a constant value.

Constant values are three types and those are –

• Numeric constants – Numeric variables having one value throughout the program execution are called numeric constants. 3.14 is numeric constant .
  For Example - 01 WS-PI PIC 9(2)V9(2) VALUE 3.14.
• Alphanumeric | non-numeric constants – Alphanumeric variables with only one value throughout the program execution are called alphanumeric constants. HI is the non-numeric constant.
  For Example - 01 WS-HI PIC X(05) VALUE "HI".
• Figurative Constants - System-defined constants are predefined in the COBOL and used as replacements for standard values like spaces, zeroes, etc. ZEROES is the figurative constant.
  For Example - 01 WS-VAR PIC 9(5) VALUE ZEROES.

Figurative Constant -

Figurative constants are system-defined keywords with predefined values. The figurative constants in COBOL are -

Figurative constant	Description
ZERO, ZEROS, ZEROES	Represents one or more occurrences of the numeric value 0. ZERO is a single 0 and ZEROS or ZEROES means two or more occurrences of 0s.
SPACE, SPACES	Represents one or more occurrences of the space. i.e., " " or X'40'. SPACE is single SPACE (" "), and SPACES means two or more occurrences of space.
HIGH-VALUE, HIGH-VALUES	Represents one or more occurrences of the high-value. i.e., X'FF'.
LOW-VALUE, LOW-VALUES	Represents one or more occurrences of the low-value. i.e., X'00').
QUOTE, QUOTES	Represents one or more occurrences of quotation mark (") or apostrophe (').
ALL	Represents one or more occurrences of the character string or figurative constant.

Comments

A comment is a non-executable statement that provides the information about code or business requirements. All computer-supported characters are allowed to write comments, and they do not affect the program's execution.

These are three types based on their usage and where they are used -

• IDENTIFICATION DIVISION Comments - Entries with optional paragraphs in IDENTIFICATION DIVISION are comments and their usage is -
  

         AUTHOR. NameOfProgrammer.
         INSTALLATION. Development-center.
         DATE-WRITTEN. mm/dd/yy.
         DATE-COMPILED. mm/dd/yy. HH:MM:SS.
         SECURITY. Program-type.

• Full line comments (any division) - Any line starting with an asterisk (*) in column 7 (indicator area) is a full-line comment. For Example -

  ----+----1----+----2----+----3----+----4----+----5
        * FULL LINE COMMENT WITH * IN COLUMN-7.

• Floating comment indicator (*>) - Comment starts in the middle of any line between 8-72 columns. For Example -

         01 WS-VAR        PIC X(12).    *> INLINE COMMENT   

Separators

A separator is a single or multiple character that separates words or strings. The table below shows the separators list -

Separator	Meaning	Separator	Meaning
	Space	:	Colon
,	Comma	"	Quotation mark
.	Period	'	Apostrophe
;	Semicolon	==	Pseudo-text delimiter

Practical Example -

Scenario - Below screenshot describes the different types of character strings in COBOL programming.

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