XML is a broadly adopted public technology, there are many authoring/generating tools, parsing/transforming libraries and many other toolkits on the market, both freely or commercially available.
Once you've designed your metadata format, you can choose from a variety of solutions to produce your metadata for application use.
While Meta Facility also provides a limited yet more Meta interface conforming compositing mechanism, that's the MetaComposition class and its nested classes.
Ableverse™ Message Facility just used this mechanism to composite message definitions extracted from Java sources into XML files, then later load these strings as metadata and compile them as message patterns to format internationlizated output for Java programs at runtime.
This mechanism is not supposed to be widely used, but if you are interested, see The API Doc for more information. And if you need supports on this, ask your questions at AVDN or consult Ableverse™ Supports.
