In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.

They are listed , usually by subject , forming a legal code ( a codex or book of law ) .
In law , codification is the process of collecting and restating the law of a jurisdiction in certain areas , usually by subject , forming a legal code , i.e. a codex ( book ) of law .