My feeling at the moment is that this might be about the only way one could go ahead in a production situation, and yes, I am familiar with PDF tools that can achieve this, though it is effectively stepping aside from ConTeXt and working with PDF. For that matter I can easily go ahead with a commercial program that solves all the problems thus far indicated. I think it is true to say that at the moment, the streams mechanism is far too klunky to be able to use it extensively. For a handful of pages (and especially if the two streams re absolutely equal in length) it is workable. Beyond that, at least for the moment, it is not, and I am afraid I do not have the luxury of time to try to refine it. Your efforts, Bruce, are hugely appreciated, but also confirm the difficulties faced thus far. Julian On 15/9/23 22:44, Bruce Horrocks wrote:

An alternate option, might be to consider producing the body matter as two 'independent' books, one with the pages on the left and page numbered 1,3,5 and the other numbered 2,4,6 and then merge them as PDF pages into the final book. Then merge frontmatter and back matter. If you are reasonably familiar with PDF splitting / joing tools then this might be the simplest solution.