Hi Eric, Chimera does not have a convenient way to move a marker placed with the path tracer tool to the highest local value in a map. A tricky way to do it is to use the Fit Model in Map tool (under menu Tools / Volume Data). If you have just one marker in a marker set you can select that marker and move it to the local maximum with the Fit button. If there are multiple markers in your marker set then all of them are moved rigidly as a group so this trick does not work so well. It would be easy to add a keyboard shortcut that would move single markers or atoms to the local density maximum. I didn't understand your explanation of why 4 points are needed for an alignment with the match command. It looks like only 3 are needed for a unique match. In your example with points ABC and DEF you suggested that the match could either pair A with D, B with E, and C with F or it could pair A with F, B with E, C with D. But the match command specifies the desired pairing so only one of those is possible for any match command invocation. Tom