Hallo Wolfgang!
\starttext \startfrontmatter
\completecontent[alternative=c]
\setuppagenumbering[state=start,alternative=doublesided,conversion=romannumerals]
...
\setuppagenumbering[state=start,alternative=doublesided,conversion=numbers] \setuppagenumber[state=start,number=1]
\stopfrontmatter
\startbodymatter
...
\stopappendices
\stoptext
This example doesn't produce roman numerals with
I can see, that this is working, but I do not understand why this complicated way is necessary nor can I understand why the above is not working. Is the normal(?) behaviour broken and the solution in your url a workaround? These are the context things which are very frustrating for a normal user and one may come to the conclusion that only the enlightend guru can use this system. Wolfgang