Help Needed Repairng Mirrored Objects in 3DSMax

Hi,

I have a short question about moddeling in 3dsmax. When one mirrors a part of an object this can cause the faces of polygons to become inverted and strangely missaligned. This causes weird wholes and shadows on the model's surface. 3dsmax has a function that repairs these errors. Does anyone now what it's called? I read about it on this very forum somewhere, but, for the life of me, I cannot remember the name.

Cheers,

Jefferies