You can use command modifiers to help you locate points or select objects while a command is in progress. Use the Coordinate Filter, Direct Distance Entry, From, MTP, and Tracking command modifiers at any prompt that requires point specification. Use the Selection Mode command modifiers at any prompt that requires object selection.
Combines X, Y, and Z values from different points to specify a single point
Locates the next point at a specified distance in the direction of your cursor
Locates a point offset from a reference point within a command.