It can be understood that the direction of material increase is 0.2 and the direction of material decrease is 0.4.

Interpretation of tolerance profile;

Surface contour refers to the state that the surface of any shape on the part maintains its ideal shape. Surface profile tolerance refers to the allowable deviation of the actual profile of a non-circular surface from the ideal profile surface. That is, it is given on the pattern to limit the variation range of the actual surface machining error.