identifiers

                                              identifiers

• identifiers are the names used for variables.types function and label in program
• they must differ in spelling and case from the keywords
• these are created by specifying it in the declaration of a variable type or function

rules for identifiers:

1. first character must be alphabet
2. must consists of only letters,digit,underscore
3. only first 31 characters are significant
4. cannot use a keyword
5. must not contain white space