KDE team removes support for underscore, starts enforcing STD3 from RFC1122
Jan 15, 2010, 15:32 (7 Talkback[s])
Re-Imagining Linux Platforms to Meet the Needs of Cloud Service Providers
"Interestingly, the latest build of KDE 4 (4.3.90 aka 4.4 RC1)
no longer supports the underscore character in host names.
"While this was allowed in previous KDE4 versions, the KDE team
have removed support for the underscore as "STD3 requires all DNS
domain names to be limited to Letters, Digits and Hyphen."