Another font problem

Another font problem

[Thomas A.Schmitz]

I just ran into a smallish yet annoying font problem. After getting the 
Adobe Type Classics for Learning CD, I prepared a couple of fonts for 
work with ConTeXt. I was mostly successful. I wanted to have a Garamond 
with oldstyle figures as default, so I used a custom encoding vector; 
the only difference to texnansi was zerooldstyle etc instead of zero 
etc. This works well, but: in German, (mainlanguage[de]), I can't get 
the baseline double quotes to work. In the "normal" Garamond, "` in the 
source produces the desired result. In the oldstyle Garamond, I don't 
get the ligature (character 132 in texnansi), but instead what appears 
to be two commas juxtapposed. I assume this is some fallback defined 
somewhere. So the question is: what feature defines this ligature? It 
is language-specific and works only wihtin German text. And, more 
importantly: why doesn't this work with my modified texnansi-variant?

Best

Thomas