A concatenation expression consists of two operands separated by the concatenation operator. 
            
            
               General Format
               
                
               
             
            
            
               Syntax Rules
               
               
               
                  
                  - Both operands must be of the same class, except that a figurative constant may be specified as one or both operands. Neither
                     operand must be numeric. Neither literal-1 nor literal-2 must be a figurative constant that begins with the word ALL. 
                  
- The length of the value resulting from concatenation must be less than or equal to 160 character positions.
 
            
            
               General Rules
               
               
               
                  
                  - The class of the concatenation expression resulting from the concatenation operation must be: 
                     
                        
                        - When one of the operands is a figurative constant, the class of the literal or concatenation expression that constitutes the
                           other operand, or 
                        
- When both of the operands are figurative constants, the class alphanumeric, or 
- The same class as the operands. 
 
- The value of a concatenation expression must be the concatenation of values of the literals, figurative constants and concatenation
                     expressions of which it is composed. 
                  
- A concatenation expression must be equivalent to a literal of the same class and value, and may be used anywhere a literal
                     of that class may be used.