The platform's base service level.

This is the basis for the contract with the product as to what the minimal set of services that are available in the platform will be. Features can be enabled on top of this most-basic level, but some features will require a higher basic level of support.

These were initially based on the product definitions that are used to provide the basis for all other products:

bringup.gni (Bootstrap) +--> minimal.gni (Minimal) +--> core.gni +--> (everything else)

The `Utility` level is between `Bootstrap` and `Minimal`, adding the `/core` realm and those children of `/core` needed by all systems that include `/core`.

The standard (default) level is `Minimal`. It is the level that should be used by products' main system.