$@

Current target’s full name (path, base name, extension), as currently specified.

$$@

Current target’s full name (path, base name, extension), as currently specified. Valid only as a dependent in a dependency.

$*

Current target’s path and base name minus file extension.

$**

All dependents of the current target.

$?

All dependents with a later timestamp than the current target.

$<

Dependent file with a later timestamp than the current target. Valid only in commands in inference rules.