Is the FRM Handbook official study material?

Guys is the FRM Handbook 6e part of the official curriculum? Are test-takers supposed to study this in addition to the 4 books you buy from them or are they interchangable?

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Not required. And I’ve heard you can use it instead of the 4 books.

Is it a better source of information than the 4 books or Schweser/BT?

When I started FRM, I was told to use the handbook, and did not. I used Schweser and didn’t feel it adequately prepared me for the test. Since I haven’t used itl, I cannot give you a reliable answer, though.