XML Companion, The, Third Edition

Document type declaration

There is another way to create a parameter entity declaration for an external entity. A single, un-named declaration can be embedded within the document type declaration, before the start of the optional internal subset. This declaration was introduced in the previous chapter.

A name is not needed for this entity, because there can only be one reference to it, and this reference automatically occurs at the end of the internal subset. The URL for this external entity is preceded by the 'SYSTEM' keyword:

<!DOCTYPE book SYSTEM "declarations.xml" [
  <!-- INTERNAL DECLARATIONS -->
  ...
  <!-- "declarations.xml" INSERTED HERE -->
]>

The implied insertion point for the entity content is very significant. It should be recalled ...