Use of "Direct" flag in UI Page form | General Information
Overview
When you create a UI Page, you will notice a "Direct" flag, a.k.a, boolean field present in UI Page form. When you hover over to the field label, it mentions ""Omit standard HTML header and JavaScript" which means that this field controls whether ServiceNow components such as their standard header (HTML), styling (CSS) and JavaScript (script dependencies) should be loaded to the UI page or not.
Example
If you set "Direct" flag to false (by default), you will see all the necessary components loading up:
If you set "Direct" flag to true, you will see all the ServiceNow components not loading up:
The latter screenshot implies that it lets developers to make completely custom UI pages.
Additional Information
- Please do note that ServiceNow macros such as jelly tags won't work if "Direct" flag is set to true. For example, "<g:ui_reference>" is a jelly tag that implies a reference field and behaves like a normal ServiceNow form type reference field. IF you set the flag to true, then all script dependencies and styling will be ruled out and you will see a normal text box (as shown in above screenshot)