"_" in hostnames

["Denis A. Doroshenko" <cyxob_(_at_)_tipas_(_dot_)_lt>]

Hello!

The topic was talked in OpenBSD miscellaneous mailing list sometimes ago
(Jul 98?) and everybody said "uderscore in host names is bad". Now here
i'm reading technical specification for one project (uhm, there's written
it's confidential), and there're many times mentioned usage of host names
with "_", wich surely will have DNS RR's. Am i misunderstanding something
or it's really bad? RFC 1033 (Domain Administrators Operation Guide, Page 4)
says:

---[RFC 1033]------------------------------------------------------------------
	...
	A domain name is a sequence of labels separated by dots.
	...
	The domain system allows a label to contain any 8-bit character.
	Although the domain system has no restrictions, other protocols such
	as SMTP do have name restricitions. Because of other protocol
	restrictions, only the following characters are recommended for use
	in a host nam (besides the dot separator):

		"A-Z", "a-z", "0-9", dash and underscore
		                              ^^^^^^^^^^
	...
---[EOrfc]---------------------------------------------------------------------