Hello. First of all read document “MIPS32® 24K(c)f™ Processor Core Datasheet”, section “Pipeline Flow”. The section describes all stages of the pipepline. IR, Ik, IT are MIPS16e only. But in other document, section “A brief guide to the 24K® core implementation” considers IT state as an obligatory stage of the pipeline. I think that is the reason of difference.