This command appears in the Matrix menu. It allows direct specification of the number of rows and columns of a matrix. In this window, you can also define a range for X-values and Y-values. These X and Y ranges will be used in new plots as the initial scale ranges. They are also available via the x and y variables if you choose to define the contents of the matrix with the Set Values Dialog.
You can also define a Long Name, Units and Comments for X / Y / Z coordinates under the X Labels, Y Labels or Z Labels tab. These labels can be used as X / Y /Z axis labels in 3D graphs.