AC Jazz aircraft are going to an all IRS fleet. The AHRS are a pain, and so is the Litton IRS, so they will have a Honeywell Laseref V in every CRJ, whether 100, 200, or 705. AC333, spefically it means EFIS comparison monitor, meaning that a parameter on the two EFIS displays do not agree. It will be accompanied by an amber box annunciator on the PFDs, next to the parameter that is causing the message. Probably heading, as the two fine gentlemen suggested.