[Groff] groff_char.7: can't find special character 'xx'

[Carsten Kunze]

Hello,

are there special characters missing in groff?  I get the following warnings in 
an UTF8 locale:

$ tbl /usr/local/share/man/man7/groff_char.7|nroff -mandoc >/dev/null
/usr/local/share/man/man7/groff_char.7:811: warning: can't find special 
character `\o'
/usr/local/share/man/man7/groff_char.7:1038: warning: can't find special 
character `bs'
/usr/local/share/man/man7/groff_char.7:1179: warning: can't find special 
character `radicalex'
/usr/local/share/man/man7/groff_char.7:1182: warning: can't find special 
character `sqrtex'