Currently a character is protruded if its rpcode/lpcode is set and it can be reached from the margin by skipping skippable items. These items are various kerns, glues, empty boxes etc. always with width 0pt. Maybe this could be extended by adding up the horizontal movements of non-zero kerns, non-stretchable glues etc. and when a protrudable character is reached and the total movement to there would be 0pt, the character would still be protruded. E. g. protrusion could happen after a \kern1sp\kern-1sp pair or after \kern1sp\hskip-1sp. Would this make sense? E. g. Robert told that (cancelling?) kerns are sometimes used as markers... Or, what if one would completely ignore/skip over all invisible items (kerns, non-stretchable glues, even with width != 0pt) and would just shift the first protrudable character? This would mean, that indented characters would be also protruded relative to indentation. Regards, Hartmut