When a device is a multiple user device – an iPad used by parents AND school children – there is the desire to limit or restrict access for the child but not the parent. How might this be done? Perhaps a 6 digit (or so) pass code can be used to enable access for a certain time period. The pass code and time duration might be settings in the profile.
Now without the granted access, any existing calendar schedule will govern access as it normally does but if the pass code is entered, it will rule over the calendar and always permit access for the duration, even if the calendar is set to deny it.
An example might be – a child is permitted YouTube access per a calendar schedule but if the parent uses the same device and desires to view YouTube and the calendar is denying it, they simply enter the pass code and have access for the time period. The iPad can then be used by child and parent with normal restrictions for the child but without restrictions for the parent, provided they have the pass code.
The router provides an authenticating proxy server to handle multiple users sharing one device. Once you authenticate yourself with a proxy username, then the profile for the proxy user applies, overriding the device profile.
This works well for computers where each user has a different account, and you can configure your browser to use the authenticating proxy server. Not sure what you can do on an iPad.