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  CLASS: UDFEAPrefix     --DVM
  PUBLIC METHODS:
    UDFEAPrefix()    - Constructor needs an offset into the enclosing
                     structure. 
    operator!=()     - Returns False if equal.
    attrType()       - Gets the value of the attrType field.
    attrSubtype()    - Gets the value of the attrSubtype field.
    id()             - setter/getter
    attrLen()        - setter/getter
    implUseLen()     - setter/getter
    void clear()     - Clears out all fields except for attrType
    void toISO()     - Copies contents to supplied byte pointer
    void fromISO()   - Initializes contents from byte pointer
    checkValidity()  - Checks reasonableness of fields.
    error()          - Returns error if any field in error.
 
  USAGE NOTES:
   User notes go here.
  
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