Data items of a Computer Program are recognized with the help of Identifiers. Identifiers serve to identify data items. Programming requires use of Identifiers. We can associate Identifiers with digits, alphabets, alphanumeric strings, and boolean values. RULES FOR IDENTIFIER FORMATION: ( 1 ) Composition of Identifiers: Only alphabet(s), underscore(s), or digit(s) can come together to form Identifiers. ( 2 ) First Occurence Particulars: An Identifier is declared to be invalid if a digit occurs in the Identifier at the first place. Either an alphabet , or an underscore (_) can be the occupant of the first place of a well-formed Identifier. One must be careful about the placement of digit(s). ( 3 ) Case Sensitivity Matters: Uppercase and lowercase letters have a distinct identity. 'N' and 'n' are altogether different. 'R' and 'r' are treated differently from each other. ( 4 ) Impermissible White spaces: White space inclusion anywhere in an identifier ...