With few exceptions, most files types can be used on your website. By default, CMS4Schools and Calendar4Schools allow most commonly-used files. A list of optional files is provided and it's up to you which file types to add to the 'allowed' list. This Help Doc describes how to add acceptable file types of your choice.
Permissions to Access this Information
To have permissions to the "Allowed File Types" in the Users Database, within the 4Schools tab, Permissions subtab, User Accounts Administrator section the 'Yes, this user can edit User Accounts" and the '4Schools (User Info tab & User/Password on Account Info tab)' check boxes must be checked.
Don't forget to click Save!
Where is the list of allowed file types?
There are a couple places you can access this list. See the screen shot above for one of them.
A second option is from the Main Web site Administration window.
Click to go 'Back to 4Schools.'
The 4Schools Welcome Screen
To see the allowed file types, click on the link on the right side of the Welcome to 4Schools window.