CARJ1 CREW HAD A L REV UNLOCKED MESSAGE. THE CREW DIVERTED TO THE NEAREST SUITABLE ARPT.

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DURING CRUISE AT FL270; L REV UNLOCKED CAUTION MESSAGE APPEARED; ALONG WITH AN AMBER REV ICON ON L N1 GAUGE; AND L REVERSER EMER-STOW LIGHT ILLUMINATED. THERE WAS NO ACFT BUFFET FELT. AUTOTHROTTLE RETARDER DID NOT ACTIVATE. FULFILLED MEMORY ITEMS AND REFERRED TO QRH. INITIALLY WAS CONFUSED BY 2 THINGS: 1) THE REV-UNLOCKED MESSAGE IS A YELLOW CAUTION MESSAGE; BUT ITS QRH PROC IS IN THE RED EMER SECTION; AN INCONGRUITY THAT HAS CONFUSED MANY A FLT CREW OVER THE YRS. 2) THE REVERSER; IN THIS CASE; DID NOT ACTUALLY DEPLOY; AND THE AUTOTHROTTLE RETARDER DID NOT ACTIVATE; GIVING RISE TO THE QUESTION OF HOW EXACTLY TO PERFORM QRH MEMORY ASSOCIATED WITH THE PROC; WHICH STATES: THRUST LEVER -- CONFIRM AT IDLE; EMER-STOW SWITCH -- PUSH. IN OTHER WORDS; IS IT NECESSARY TO BRING THE THRUST LEVER TO IDLE OURSELVES IF THE AUTOTHROTTLE RETARDER DID NOT ACTIVATE PRIOR TO PUSHING THE EMER STOW BUTTON? THE QRH DOES NOT ADDRESS THIS POSSIBILITY. WE ASKED FOR AND RECEIVED A CLRNC TO DSND; AT WHICH POINT THE THRUST LEVERS WERE RETARDED TO IDLE AND THE EMER-STOW BUTTON WAS PUSHED; COMPLETING THE MEMORY ITEMS. STILL UNSURE ABOUT THE REMAINDER OF THE PROC (SEE #1 ABOVE); WE QUESTIONED WHETHER A DIVERSION TO LAND AT THE NEAREST SUITABLE ARPT WAS REQUIRED OR NOT; SO CONSULTED IN CONFERENCE CALL WITH DISPATCHER AND MAINT CTL; AND ALTHOUGH NEITHER PARTY ON THE GND PROVIDED DEFINITIVE GUIDANCE INITIALLY; I FELT IT WAS IN THE BEST INTEREST OF SAFETY TO LAND AT THE NEAREST SUITABLE ARPT; AND ALL PARTIES CONCURRED ON A DIVERSION TO ZZZ. WE NOTIFIED ATC OF OUR NEED FOR A PRECAUTIONARY DIVERSION TO IND FOR POTENTIAL THRUST REVERSER PROB; THEN INFORMED FLT ATTENDANT AND PAX. WHILE INBOUND TO ZZZ; CONTACTED IND STATION TO INFORM THEM OF OUR IMMINENT ARR. AFTER ARR AT ZZZ; DISPATCH AND MAINT CTL WERE RE-CONTACTED; PAX WERE DEPLANED; ACFT WAS WRITTEN UP; AND DISPATCH RELEASE AMENDED. CONTRACT MECH MET THE ACFT IMMEDIATELY AND SECURE; DEACTIVATED THE L THRUST REVERSER; DEFERRING IT UNDER DIRECTION OF MAINT CTL. ONCE MAINT ACTION WAS COMPLETED; ACFT WAS RE-DISPATCHED IND-CVG WITH REMAINING PAX; WHO WERE TOLD THAT THE THRUST REVERSER IN QUESTION HAD BEEN DEACTIVATED AND LOCKED SECURELY IN A SAFE CONDITION SO AS NOT TO CAUSE ANY FURTHER PROBS. FLT PROCEEDED TO CVG WITHOUT FURTHER INCIDENT. AFTER THE INCIDENT; TALKED TO RJ PROGRAM MGR; WHO ELIMINATED MY CONFUSION OVER THE THRUST REVERSER MESSAGE AND QRH PROC; SAYING NOT TO WORRY; WE WERE NOT THE FIRST CREW TO BE CONFUSED OVER IT. HE EXPLAINED FURTHER BACKGND INFO AND HELPED IMPROVE MY UNDERSTANDING OF THE ISSUE. HE SPOKE OF ADDITIONAL GUIDANCE THAT USED TO BE INCLUDED IN THE QRH PROC; BUT HAS SINCE BEEN REMOVED FOR SOME REASON. I DID; THEN; REMEMBER WHEN THAT ADDITIONAL VERBIAGE USED TO BE THERE; AND PERHAPS I WAS CONFUSED; BECAUSE SUBCONSCIOUSLY; I EXPECTED TO STILL SEE IT THERE. AS IT TURNED OUT; ALL OUR ACTIONS DID EFFECTIVELY ACCOMPLISH EVERYTHING CALLED FOR IN THE QRH PROC.