[RFC] adding a Schema validation

A great feature of XML is that you could validate a given XML file with another file.
In that file you could define the schema of the file with default values, optional values, children, data types etc.

In some env the schema is a killer feature, its usage should be suggested as best practice.

The schema file could be called
TOSF - Schema File
TOSD - as XSD
TOLO - Liuggio Obvious