The following example shows how the ASN.1 syntax might define a CHOICE.

    A ::= CHOICE
          {
              x INTEGER,
              y OBJECT IDENTIFIER,
              z OCTET STRING
          }

The application program can choose to have field b be an INTEGER, an OBJECT IDENTIFIER, or an OCTET STRING. If the application program chooses for it to be an INTEGER, the following string should be specified:

    b (x 1234)