These are two lines from the GL_EXT_vertex_weighting section of the glext.h header file:
#define GL_MODELVIEW0_MATRIX_EXT GL_MODELVIEW_MATRIX
#define GL_MODELVIEW_MATRIX1_EXT 0x8506
If I’m not mistaken, shouldn’t the latter be GL_MODELVIEW1_MATRIX_EXT? Maybe this has already been pointed out, but the last I checked, the glext.h file on SGI’s site still had the error. Maybe I was looking at an old one, though.