The ornamental design for an interiorsurface for a squash court, as shown and described.
FIG. 1 is a perspective view of an interior surface for a squash court
showing my new design;
FIG. 2 is an elevational view of the portion of my design on the front wall
thereof;
FIG. 3 is an elevational view of the portion of my design on the right-hand
side wall thereof, the design on the left-hand side wall thereof being a
mirror image of the design on the right-hand side wall; and,
FIG. 4 is a top plan view of the portion of my design on the floor thereof.