character_expression ::=
 {
     character_constant_name
   | character_function_call
   | character_literal
   | character_variable_name
   | :host_variable_name [:indicator_name]
 }
 [|| {
         character_constant_name
       | character_function_call
       | character_literal
       | character_variable_name
       | : host_variable_name [:indicator_name]
      } 
 [|| {
        character_constant_name
       | character_function_call
       | character_literal
       | character_variable_name
       | : host_variable_name [:indicator_name]
     } ]...