mandoc output to ascii - plaintext?

[Jiri B]

Hello,

I wanted to grep a pattern from a manpage and was
very surprised I do not get "normal" plain text.

$ mandoc /usr/local/man/man1/context.1 | cat -ntve | sed -n '123,124p'
   123         -^H--^H-v^Hve^Her^Hrs^Hsi^Hio^Hon^Hn$
   124                report installed context version$

karl.example.com (00:44:27)
karl(ttyp3) [/tmp]
$ mandoc /usr/local/man/man1/context.1 | grep version                  
       version of the ConTeXt typesetting system, an extensive macro package
              report installed context version

Is this expected behaviour? I really don't understand much
'ASCII Output' section of mandoc manpage.

jirib