HISTORY The original version of this random number generator used the RC4 (also known as ARC4) algorithm. In OS X 10.12 it was replaced with the NIST-approved AES cipher, and it may be replaced again in the future as cryptographic techniques advance. A good mnemonic is ``A Replacement Call for Random''.

訳すと RC4(ARC4とも言う)アルゴリズムの実装だけど OS10.12で AESに変わったし、後にまた変わるから、 A Replacement Call For Random の略として覚えると良いよ (edited)