Why Positive and Negative J-integral values by ANSYS?

I did evaluation of J-integral distribution along a 3D semi-elliptical internal surface crack in a thick-walled pressure vessel using ANSYS APDL. The results I got included positive and negative values. Sometimes the values were all positive or negative and in other cases, negative and positive values were combined. What could be the interpretation of negative and positive values in ANSYS. I seriously seek assistance from someone.