AFAIK - "as far as i know". It indicates a certain level of uncertainity.

Anyway - I've not performed RMAN BMR. But look at the below RMAN userguide and procedures for performing BMR. There is nothing there which explicitly or implicitly indicates that one absolutely requires a catalog. It's just a "blockrecover..datafile..restore" command. I don't see why this would *require* a catalog.

http://download-west.oracle.com/docs...ov.htm#1008024

(Pay attention to - Recovering data blocks with RMAN).

I'd be interested in knowing why one needs the catalog for BMR, if you can lookup the information from the book.