allowing underscores in A/AAAA records

[Jack Tavares]

It seems that some people like to put underscores "_" in their
hostnames.
 
This seems to be popular in Microsoft centric organizations.
 
If they then enter this as an A (or AAAA) record in bind, an error
is generated. (Rightly so).
 
One can turn off check-names or set it to warn so that the zone
still loads.
 
One can run named-checkzone -k warn|ignore.
 
But I would like to be able to allow underscores and still validate
the rest of the label. (ie: check that label length is not longer than 
the max, the total length of the domain name is not too long,
no _other_ invalid characters, etc)
 
I don't see a way to do this other than to write my own
name validation routine.
 
Is there a way to do this?
 
Thanks
--
Jack Tavares
NOTE:  I am at GMT+2