Something that has worked for me in the past is not working for me at 
the moment, and I cannot figure out why:

\startsectionblockenvironment [frontpart]

\setupuserpagenumber [numberconversion=romannumerals]

\setcounter [userpage] [5]

\stopsectionblockenvironment

\startsectionblockenvironment [bodypart]

\setcounter [userpage] [1]

\stopsectionblockenvironment

gives me roman numerals in the TOC but not on the frontmatter pages, 
which are arabic. Bodymatter is okay. What could I possibly be doing wrong?

Even with a different setup I get the same result:

\definestructureconversionset [frontpart:pagenumber] [] [romannumerals]
\setupheads[title][sectionconversionset=section]
\startsectionblockenvironment[frontpart]
\setupuserpagenumber[numberconversion=romannumerals]
\setuppagenumber[number=1]
\stopsectionblockenvironment

Puzzling (for me at least).

Julian