I've passed the Section IX, B31.1 and B31.3 exams. They are structured similar to the D1.1, D1.5, or API 1104. You will be asked a question and you will have to find the information, text or data, in the applicable code section. You need to be familiar with how the code section is "constructed" meaning you need to know what article or chapter contains the information you are seeking.
The CWI questions do not require "interpretive" answers. The goal of the examination is to verify you know the layout of the code to the extent you can look up answers quickly and accurately. There are sufficient numbers of questions you will not have enough time to finish the examination if you are unfamiliar with the code.
Best regards - Al