YaX is advertised as a key system, but it rather organizes attributes in parameters, which parameters can be executed, so that YaX is halfway between key management and macro definition (and actually hopes to provide a user’s interface).

Values assigned to attributes can be retrieved and tested in various ways, with full expandability ensured as much as possible.

Finally, YaX’s syntax is a quite peculiar (as few braces as possible), but may be customized.

YaX is based on texapi and thus requires e-TeX.