/blog/post/5595163 TATA/ROU was always a slip (whose 1970 inauguration isn't confirmed in your post). In 1983 TT, 89A TATA portion got clubbed at ROU to 89/90 Steel City (ex Bokaro via Hatia). 89/90 Steel City never started ex TATA (so never reversed ex ROU). TATA Slip must got introduced when 89/90 Steel City stopped touching HWH!!
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