XF 1.5 /install question

[Reaks Lobby]

Hello , I wanted to know what was using the " rebuid master data " option in the / install ?
Thank you...
Best regards

 

[Arty]

Its an emergency button that reuploads global stuff that should not be messed with: master style (not default style, its parent of default style that is visible only in debug mode), email templates, phrases.