<<< Of course, just because an English sentence has proper spelling, grammar, and punctuation doesn't make it meaningful:
The brick astonished the sunlight.
Similarly, there are some questions about the weather report that the DTD can't answer:
To be able to do this level of validation, the W3C has created XML Schema, a markup language that lets you describe how other XML languages are to be validated. Since XML Schema is itself in XML, it's much easier to read than a DTD. [Note: This material is based on the excellent XML Schema primer available at the W3C website.] Let's start with the skeleton of an XML Schema to describe EWEML
<schema xlmns="http://www.w3.org/1999/XMLSchema" xmlns:ewe="http://catcode.com/eweml" targetNamespace="http://catcode.com/eweml"> </schema>
Since the schema uses XML tags to define another set of XML tags, the attributes in the opening <schema> tag establish namespaces so that we can know whose tag names are whose.
In detail, the attributes in the opening tag mean:
The things that look like web addresses are used to uniquely identify each of the two markup languages that we're dealing with.
Now let's fill in some of the schema. >>>