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Using the Concrete Syntax Scope

When defining the syntax, we did not discuss the scope of the syntax, that is what data is governed by the delimiters and other parts of the syntax which were defined there. The SGML declaration allows the concrete syntax used in the DTD to be different from that in the document instance. This can be useful for public DTDs which use a syntax different from the syntax a particular group is used to using (for example, the public DTD may use the reference concrete syntax while the document uses a local variation). You select the scope of the defined syntax by specifying one of the two following choices:

DOCUMENT

indicates that the DTD and the document instance (the document data and markup which follows the DTD) both use the declared syntax. Remember that the SGML declaration always uses the reference concrete syntax. Also remember that the entire SGML document must use the document character set defined above.

INSTANCE

indicates that only the document instance is marked up using the syntax that is being defined. In this case, the DTD, like the SGML declaration, must use the reference concrete syntax.

The following example shows the specification which indicates the scope of the defined syntax is the entire document, not just the document instance.

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