Ratio 18:9 or 16:9?


Hi Jordy & Cinecom Staff,
I am Johnson, from Hong Kong. I am your audience since I need to prepare my wedding video.
I have a question, when I am using your storyboard layout for my preparation, I found that the layout board scale is 16:9, but the dot line is 18:9, how did you decide which scale will you choose?