Standard Reference Videos (SRCs) are used to verify the electronics and optics of the VetStat analyzer. To ensure optimal performance, IDEXX recommends confirming SRC measurements within acceptable ranges once daily on each day the device is operated. Three levels of SRC are available for the VetStat device; each tests a different optical range. The multi-level SRC is provided as part of the initial device shipment because it measures high, normal, and low optical ranges. These special test cassettes contain a stable optical simulator measured by the device in exactly the same way as with other cassettes, providing confirmation that all measured parameters are consistent. The results obtained should fall within the limits supplied with the SRCs.