cf
FieldAncillary.
isauxiliary
True if the variable is an auxiliary coordinate object.
See also
isdimension, isdomainancillary, isfieldancillary, ismeasure
isdimension
isdomainancillary
isfieldancillary
ismeasure
>>> f.isauxiliary False
cf.FieldAncillary.hour
cf.FieldAncillary.isdimension