definiens: shall mean transcription - based nucleic acid amplificationusing reverse 1ranscnptase, RNA polymerase and added RNase H, wherem(a ) the added RNase H molecule contains no enzyme activity found in reversetranscriptase other than that of bmding to the RNA and cleaVingthe RNA strand of anRNA : DNA duplex;(b ) the added RNase H is present at greater than or equal to 0.00Iunit / microliter ( where the urnt delirii1lOnand assay condItions are eqUlvaIent to those setforth below ) m the amPlification reaction or, Ifpresent m lesser amount, tile extent ofampIihcatlon achieved m the presence of such aaded RNase H shall be at least 10 timesgreater than achieved m tile abSence of such added RNase H ; and(c ) the amplification reaction is performed at a temperatJire below 55 degreesc