CSN1String :
    SendExpression
|   Alternation
|   Intersection
|   Exclusion
|   Concatenation
|   BASIC_NAME ExponentExpr*
|   BasicString ExponentExpr*   
            
      
A CSN.1 string defines a set of acceptable bit strings. Strings are combined using various operations. These operations are given in order of precedence, highest to lowest:
Table 17.1. CSN.1 Operations from highest to lowest precedence.
| 
                                 exponentiation (an exponent is applied to indicate repetition)  | 
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| 
                                 concatenation  | 
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| 
                                 exclusion (disallowing certain strings that would otherwise be accepted)  | 
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  | 
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| 
                                 send (specifying a particular string the encoder should send, allowing decoders to accept other strings too)  | 
              
        
      
The BASIC_NAME in the sixth alternative shall not be a multi-word name.