"Royal Flags Wave Kings Above" I'm a starter to cryptanalysis and in fact to cryptology. Last night I was decrypting a message from a book that I would quite odd. It doesn't make sense. The decrypted message is "Royal Flags Waves Kings Above". 

This is what the book says:
"The plaintext message is a mnemonic to remember the turnover positions on the first five Enigma rotors."

My question is what the message means? What does it have to do with Enigma?
A quick internet search delivered this description of Enigma:


  "This meant that the notches were engaged when Q, E, V, J and Z were uppermost on rotors I, II, III, IV, and V respectively and that therefore the turnover positions were R, F, W, K, A, remembered by the cryptanalysts at Bletchley Park by the mnemonic Royal Flags Wave Kings Above."


So this seems to be the right message yes.