On Mon, 3 Sep 2007, Javier Múgica de Rivera wrote:
2. Other idea I would like to propose is making \phantom a primitive. The idea behind \phantom is that it is as if you actually typed the material, but it finally does not show up, as if it were printed with invisible ink. The current definition of \phantom does not fulfil this idea. In particular, it generates Ord items in math. This is specially anoying for delimiters. It has some other drawbacks; it kills the stretching and shrinking of glue, so the "phantommed" material may not actually occupy the same space as real material, possibly in a line just above or below, resulting in misalignments. Now that nodes can have attributes, maybe could phantomness be one of them.
once i had played with \pdfoff blabla\pdfon, it simply didn't output anything (also no characters were marked as used) but all movements were still done internally, and finally it positioned to the point where it should proceed with visible stuff. This worked global, even over page borders. Maybe it would fit into your concept. Regards, Hartmut