Description: Returns or changes the default vertical motion index. The unit of measure for VMI is centipoints per line. The POS indicates the supported values. An unsupported value causes the printer to use the closest supported value, causing the printer to return . Additional information: When an attempt is made to set this to an unsupported value, LaserJet 4500 will return rather than returning and the value of this object will not change. This is contrary to what the General Description says but is consistant with other LaserJet products (LJ5, LJ5Si, LJ4500). This object can be set when the printer is not idle, and will return if successful, but the change will not affect the current job since the printer's default value, not the current value, is being changed.