Final answer:
TIR does not have a defined meaning in the given context, and the reference 'E5-E6-9' does not match provided material. TIR often stands for 'Target Internal Rate' in business, but without context, a definite answer cannot be given.
Step-by-step explanation:
The acronym TIR is not explicitly defined in the context of the provided reference information. Often TIR stands for Target Internal Rate or Total Internal Reflection, but without a specific context, it is unclear which pertains to your question. However, judging by the surrounding terms such as Economic profit, Economic surplus, and economic unions, it seems more likely that TIR here relates to a concept in an economic or business context, rather than the physics term "Total Internal Reflection".
Unfortunately, within the provided reference material, there are no page numbers or keywords that match 'E5-E6-9' directly or suggest what TIR could stand for. If 'E5-E6-9' is meant to refer to pages in a textbook or specific entries, it would be best to look at those pages or entries to obtain the context needed to provide a precise definition of TIR.