FAILED TO HOLD SHORT EXTENSION OF RWY 10L PER CLRNC.

Narrative

WHEN WE REQUESTED TAXI CLRNC; GND CTL RESPONDED; 'TAXI TO RWY 10L'. DUE TO OPERATIONAL CONSIDERATIONS; WE REQUESTED RWY 10R. GND CTL THEN RESPONDED; 'TAXI TO RWY 10R; HOLD SHORT OF 10L'. REFERRING TO THE ARPT DIAGRAM ATTACHED; I INTERPRETED THIS CLRNC TO MEAN TAXI VIA THE PATH SHOWN IN YELLOW; HOLDING SHORT OF RWY 10L. (THERE WAS ANOTHER ACFT IN POSITION TO TAKE OFF ON RWY 10L.) AS I STARTED DOWN TAXIWAY D; THE GND CTLR CALLED AND SAID; 'THAT'S RIGHT TURN THERE'. WE ACKNOWLEDGED AND TURNED R ONTO THE PARALLEL TAXIWAY HEADING WBOUND. OUR ACTUAL TAXI ROUTE IS SHOWN IN RED ON THE DIAGRAM. AS WE PROCEEDED TO RWY 10R; WE SAW NO SIGNS OR MARKINGS INDICATING A HOLDING POINT FOR RWY 10L AND BY THIS TIME; WITH THE CONFUSION ABOUT THE TAXI ROUTE; I HAD NOW ZEROED IN ON TAXIING BY THE 'NEW' ROUTE WHICH SEEMED NOT TO CONFLICT WITH RWY 10L. THE OTHER ACFT DEPARTED ON 10L AND WE WERE THE ONLY TAXIING ACFT AT THE ARPT. AS WE ROUNDED THE CORNER ON TAXIWAY L AND APCHED RWY 10R; WE CALLED FOR TKOF CLRNC. THE TWR CTLR RESPONDED; 'HAVE YOU PASSED 10L'. WHEN WE REPLIED IN THE AFFIRMATIVE; HE TOLD US THAT OUR CLRNC HAD BEEN TO TAXI TO 10R; HOLDING SHORT OF 10L. WHEN YOU PUT IT ALL TOGETHER; I GUESS IT MAKES SENSE BUT THERE MUST BE A BETTER WAY. SOME SUGGESTIONS: INSTEAD OF THE STANDARD 'HOLD SHORT OF RWY XXX'; I THINK BETTER WORDS WOULD BE; 'HOLD SHORT OF THE RWY XXX FINAL APCH PATH'. SINCE THE INCIDENT WAS AT NIGHT; A LIGHTED SIGN AT THE HOLD POINT CERTAINLY WOULD HAVE HELPED. I HAVE NOT SINCE RETURNED TO BOI TO CHECK AND THERE MAY WELL BE SIGNS INSTALLED BUT I DIDN'T SEE ANY. WITH THE POSSIBILITY OF OTHERS MAKING THE SAME MISTAKE I DID; WHY NOT TAXI TO 10R BY THE YELLOW ROUTE I HAD PLANNED ORIGINALLY. SINCE WE WERE THE ONLY TAXIING ACFT; SOME MORE HELP FROM THE GND CTLR WOULD HAVE BEEN DESIRABLE. I'M SURE THIS TYPE OF INCIDENT HAS HAPPENED BEFORE AND THE CTLRS ARE AWARE OF THE POTENTIAL FOR IT HAPPENING AGAIN. SUPPLEMENTAL INFORMATION FROM ACN 82243: THE CAPT THEN RESPONDED THAT 'JUST FOR THE RECORD TWR; WE WERE CLRED TO TAXI TO 10R.' THE TWR THEN RESPONDED THAT WE WERE INSTRUCTED TO HOLD SHORT OF 10L. THE CAPT AND I DISCUSSED THE CLRNC BRIEFLY AND AGREED THAT WE WERE INSTRUCTED TO HOLD SHORT OF RWY 10L. I DIDN'T REALIZE THAT WE HAD ACTUALLY CROSSED THE APCH PLANE OF 10L AND HAD THEREFORE CROSSED RWY 10L ALTHOUGH STILL BEING OUR ONLY TAXIWAY. CAPT NOTICED ANY HOLD SHORT MARKINGS NOR DID WE RECEIVE ANY SPECIAL INSTRUCTIONS FROM GND CTL TO DRAW OUR ATTN TO THE POSSIBLE CONFUSION OF XING 10L AT TAXIWAY.