[NTG-context] Skipping item numbers in an itemized list?

Hello, The effect I want is something like: 1. First item 2. Second item 5. Fifth item 6. Sixth item 8. Eight item and so on. Every now and then I need to skip a number or two. In LaTeX I could do this with \addtocounter{enumi}{2} - but how is this done in ConTeXt? Thanks very much, Alasdair