Are there any possible values for the 6th parameter to OpenCV's CvMat* cvInitMatHeader

Are there any possible values for the 6th parameter to OpenCV's CvMat*
cvInitMatHeader

I'm referring to the C
CvMat* cvInitMatHeader(CvMat* mat, int rows, int cols, int type, can int
step be void* data=NULL, int step=CV_AUTOSTEP) anything other than
CV_AUTOSTEP are there any other enums the 6th param could be like
cvCreateImage has:
#define IPL_DEPTH_SIGN 0x80000000
#define IPL_DEPTH_1U 1
#define IPL_DEPTH_8U 8
#define IPL_DEPTH_16U 16
#define IPL_DEPTH_32F 32
#define IPL_DEPTH_8S (IPL_DEPTH_SIGN| 8)
#define IPL_DEPTH_16S (IPL_DEPTH_SIGN|16)
#define IPL_DEPTH_32S (IPL_DEPTH_SIGN|32)
If so in what file are they #defined....