The ornamental design for a coordinate inputinstrument, as shown and described.
FIG. 1 is a top-front-right perspective view of a coordinate input instrument according to my new design;
FIG. 2 is a bottom-rear-left perspective view thereof;
FIG. 3 is a right side elevational view thereof, wherein the left side elevational view is mirror symmetrical to the right side elevational view;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines show portions of the coordinate input instrument which form no part of the claimed design. The dot-dash broken lines define the bounds of the claimed design and form no part thereof.