6.1 Declaration that SMDL is a Derived Architecture
The SMDL meta-DTD indicates the fact that it is a derived architecture by using the
APPINFO parameter of its SGML declaration. The keyword
ArcBase is specified as a sub-parameter of the
APPINFO parameter of the SGML declaration. It appears in the SGML declaration of the SMDL meta-DTD as follows:
This indicates tothe document processing system that there may be "
ArcBase" processing instructions in the SMDL meta-DTD that will specify the base architectures from which SMDL is derived.
In effect, this is an invocation of the "Base Architecture" identification facility found in Annex C of the HyTime International Standard. It does not invoke the HyTime architecture.
6.2 Identification of Base Architecture
The SMDL meta-DTD indicates the fact that its architecture is derived from the HyTime base architecture by means of an
ArcBase processing instruction. In SGML's reference concrete syntax, it would appearas follows:
This processing instruction establishes that HyTime is the SMDL meta-DTD's local name for one of its base architectures, and that aftert his processing instruction, the document processing system can expect to find:
NOTATIONdeclaration that identifies the architecture definition document (in this case, the HyTime International Standard). Associated with this
NOTATIONdeclaration must be an attribute definition list (an
ATTLIST) that declares the support attributes of the architecture. The HyTime International Standard itself defines these attributes, but this attribute definition list must also appear in e very meta-DTD derived from HyTime. The list therefore forms a part of the SMDL meta-DTD, and it appears below using SGML's reference concrete syntax.
ENTITYdeclaration that identifies the meta-DTD of the base architecture (HyTime), and which may specify values for HyTime' s architectural support attributes.
6.2.1 Declaration of Base Architecture
The following SGML
NOTATION declaration points to the HyTime International Standard. The
ATTLIST that follows it defines the attribute list of the HyTime notation. These declarations have been copied here from the HyTime International Standard.
The above declarations appear verbatim in this official version of the SMDL meta-DTD. However, in a version of the SMDL meta-DTD used in the context of a particular application, these declarations could conceivably be go verned by an SGML declaration that defines a concrete syntax otherthan SGML's Reference Concrete Syntax. In such a case, they might not look exactly like the abo ve declarations, but they would have the same effect.
6.2.2 Declaration Template for the HyTime Meta-DTD Entity
The following SGML
ENTITY declaration points to a file (here named
"myhytime.mtd") containing those formalized SGML aspects of the HyTime International Standard (i.e., those portions of the HyTime meta-DTD), which are actually in effect for this application. An
ENTITY declaration ha ving the same ef-fect as this one m ust appearin every SMDL meta-DTD document.
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