According to MARCspec 9.6 Reference to indicator values, i am trying to to do a query on 264 fields with second indicator is value "1"

->query('264{^2=\1}')

Receiving Exception:

 Detected invalid MARCspec. Invalid spec length.Spec must be at least three characters long. Tried to parse "^2" 

Not sure if the query is not correct or there is a bug in the MARCspec implementation.