[Groff] german localisation

[joerg van den hoff]

hello,
I've used groff for some years now together with a copy of ghyph31.tex 
where I commented out everything with  "%" except the pattern block. 
this seemed to work reasonably.

now, after upgrading to groff 1.18.1 (same thing with 1.19) under MacOS 
X (1.18.1 as part of OS upgrade), formatting goes into an endless loop 
at 100% cpu when using this  old hpf-file.

is this related to occurence of things like

\n{f"a1c}

in the pattern block (I found a remark in the docu that braces are not 
allowd in the pattern block)?  I have no knowledge of tex whatsoever, 
but I guess this are patterns containing german umlaut characters?

I replaced the old file by "dehyph[nt].tex" but without avail (these are 
silently ignored (no hyphenation in the output)).

question: is there a canonical way to transform the original tex 
hyphenation pattern files to groff compatible versions without knowing  
how to do macro expansion and the like in the tex files? is there a awk 
or perl script around  to do so? or are groff compatible hyphenation 
pattern files (except for us english)  somewhere around (I did'nt find any)?

thanks
joerg