ちょくれい is the standard on'yomi. 勅 (チョク) denotes an imperial command, and 令 (レイ) means an order or decree. たくれい and ちゃくれい are incorrect readings of 勅, and ちょくれいう adds an unnecessary prolonged vowel. This term specifically refers to an imperial decree or order issued by the Emperor, highlighting its origin from the highest authority rather than a general government order.

ちょくれいは標準的な音読みです。勅は「天皇の命令」、令は「お触れ」の意味。天皇が発する公式な命令や布告を指します。たくれいやちゃくれいは勅の誤読、ちょくれいうは不必要な長音です。