Spec missing CIRC PURPOSE field
CIRC events have a PURPOSE keyword field, for instance...
63 CLOSED $24518FFB7C78DAA9E1962538B544494B6AD1A7C4=FFTTZZ,<...etc> PURPOSE=GENERAL REASON=FINISHED
However this isn't reflected in the control spec. This field comes from circuit_purpose_to_controller_string of circuitlist.c so valid options are "SERVER", "GENERAL", "HS_CLIENT_INTRO", "HS_CLIENT_REND", "HS_SERVICE_INTRO", "HS_SERVICE_REND", "TESTING", "MEASURE_TIMEOUT", "CONTROLLER", and "UNKNOWN_".