[NTG-context] 3SIDE imposition schema weirdness

Hi, i'm a little bit puzzled by the results of the following test file, using the 3SIDE imposition schema from Willi ( http://wiki.contextgarden.net/Imposition#Additional_schemas ). The results consists in pages 1|2|3 on the recto of the sheet, and pages 4|5|6 on the verso. * Is it really the intended result ? * If so, I don't understand how can \dosetuparrangement{3}{1}{6}{4}{2} give 1|2|3 // 4|5|6 . What's the rationale ? Why no page 5 among the arguments of \dosetuparrangement ? * What if one wants to fold the resulting brochure ? How to adapt the code (besides by try and error) for the resulting arrangement to be 3|6|1 // 2|4|5 ? Thanks in advance, cheers, Nicolas