Hi Scott,
The full list of event codes transfer will return is below. Note that ABEND and FILE_ACCESS are deprecated, so you are unlikely to see them.
If you need any more information about what any of these codes mean or when they would come up let me know!
ABEND
ACL_CHANGED
AMBIGUOUS_PATH
AUTH
CANCELED
CLOCK
CONNECT_FAILED
CONNECTION_BROKEN
CONNECTION_RESET
ENDPOINT_ERROR
ENDPOINT_TOO_BUSY
EXPIRED
EXTERNAL_CHECKSUM_MISMATCH
FILE_ACCESS
FILE_NOT_FOUND
FILE_SIZE_CHANGED
GC_NOT_CONNECTED
GC_PAUSED
GSI_DN_MISMATCH
INTERNAL_ERROR
INVALID_PATH_NAME
INVALID_SERVICE_CREDENTIAL
INVALID_SYMLINK
IS_A_DIRECTORY
IS_A_FILE
LIMIT_EXCEEDED
MPU_NOT_FOUND
NO_APPEND_FILESYSTEM
NO_CREDENTIALS
NO_PHYSICALS
NO_SPACE_LEFT
NOT_A_DIRECTORY
NOT_A_FILE
NOT_A_SYMLINK
PAUSED
PERMISSION_DENIED
PROGRESS
QUOTA_EXCEEDED
STARTED
SUCCEEDED
TIMEOUT
UNKNOWN
UNPAUSED
VERIFY_CHECKSUM
Hope that helps,