You can save a section as a custom section and reuse it in other apps. To save a section, in the layout sections area, right click on the section you want to save. Give it a name. Now when you click on "add section" you will be able to select that custom section.
You cannot save content sections as a custom section.
Custom sections are being sunset as there are better ways to accomplish the same function. It is best practice if you want to have custom sections, create an app with all of your custom sections and then use the clipboard function to copy the sections and paste them into the apps you want to use them on.
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