[Orgmode] Unbillable clock time

[Ross Patterson]

I would like to be able to designate some of my clock time as unbillable
such that when using a clockreport the unbillable time is not included.
I would also like to compare billable and unbillable time if possible.

Currently I either manually change "CLOCK: *" to "UNBILLABLE: *"
preserving history but it's kind of messy or I just delete the time
altogether, losing history.

Is there a better way to accomplish this?  If not, may I request this
feature.  :-) Many time-keeping systems have a "billable" flag for
entries.

Ross