# SYSTEM

New in version 3.25.

Specifies that a target is a `SYSTEM` library. This has the following effects:

- Entries of `INTERFACE_INCLUDE_DIRECTORIES` are treated as `SYSTEM` include directories when compiling consumers. Entries of `INTERFACE_SYSTEM_INCLUDE_DIRECTORIES` are not affected, and will always be treated as `SYSTEM` include directories.

For imported targets, this property defaults to true, which means that their `INTERFACE_INCLUDE_DIRECTORIES` are treated as `SYSTEM` by default. If their `SYSTEM` property is false, then their `INTERFACE_INCLUDE_DIRECTORIES` will not be treated as `SYSTEM`, regardless of the value of the `IMPORTED_NO_SYSTEM` property.

This target property is initialized from the `SYSTEM` directory property when the target is created.