Different Specification Of Polygon Offset
The 1.0 polygon offset extension didn't let you apply the offset to filled primitives in line or point mode. Only filled primitives in fill mode could be offset.
In the 1.0 extension, a bias parameter was added to the normalized (0.0 - 1.0) depth value, in place of the 1.1 units parameter. Typical applications might obtain a good offset by specifying a bias of 0.001.
See the GLUT example, which renders two cylinders, one using the 1.0 polygon offset extension and the other using the 1.1 polygon offset interface.