A standard schema is used to describe the capabilities of a peripheral
device, such as a printer device, in a structured and easily discoverable
way. The schema can allow different peripheral device implementations to
describe their capabilities in a consistent way to those entities that
might query for the capabilities. The schema syntax can allow for direct
querying of individual values, as well as for querying whole sections of
the schema so that an accurate and complete understanding of the device
can be gleaned.