The SPDL structure is the result of the division and repeated subdivision of an SPDL instance into increasingly smaller parts. This process results in a hierarchical structure.
The notation employed to specify the SPDL structure is declarative in nature, as opposed to the content notation, which takes the form of a procedural language. The structure also implies a sequential order for the set of structure elements which comprise the document.
The following concepts and terminology are associated with the hierarchical structure and the relationships implied by that structure.
The elements of an SPDL document which are distinguished by
the document structure are called
A structure element which is subdivided into smaller
structure elements is called a
A structure element which cannot be subdivided into smaller
structure elements is called a
Every base structure element has a value.
The value of a base structure element belongs to one of the
types defined in The parts into which a composite structure element has been
subdivided are said to be the Since the immediate subordinates of a composite structure
element may be composite structure elements, there may be
structure elements which are the result of the further
subdivision of a composite structure element which are not
themselves immediate subordinates of that structure element. All
of the structure elements, composite or base, which result from
the further subdivision of a structure element are said to be
Reference to the immediate subordinates of a structure
element always uses the form " It is often necessary to refer to the structure element or
structure elements to which a particular structure element is
subordinate. A structure element A is said to be Reference to the immediate superior of a structure element
always uses the form " In describing the structure or processing of a structure
element Structure elements immediately subordinate to the same
structure element are called A structure element which is not subordinate to any other
structure element is said to be A structure element which is subordinate to
a DOCUMENT is called a The The In addition to a hierarchical structure, the SPDL structure
assigns a sequential order to the immediate subordinates of each
of the composite structure elements.
The combination of the hierarchical structure and the
sequential order of peer structure elements generates a
sequential order for the set of structure elements which
comprise the SPDL INSTANCE. Structure elements that
come later in this sequential order are said to
The sequential order is related to the hierarchical structure
by two rules:
Thus the sequential order has the property of being
"pre-order depth-first" relative to the hierarchical structure.
An example of the relationship of the sequential order to the
hierarchical structure is shown in
This sequential order of structure elements is also the
The term presentation order may be used to refer to the
sequential order of a subset of the structure elements within
an SPDL document. For instance, the "presentation order
of PAGE structure elements" within the SPDL document
is the order in which PAGE structure elements occur
within the sequential order of the SPDL document. The
presentation order of PAGE structure elements is the order in which
the pages of the document are presented to the user.
Each of the PAGE structure elements is assigned an
An imposition process may place two or more "logical pages"
on a single sheet. Such an imposition process is part of the
Composition and Layout Process. In the resulting SPDL document,
each PAGE structure element describes the image to be
placed on an entire sheet, which may include several "logical
pages". The SPDL Presentation Process has no knowledge of the
component logical pages, but only of the PAGE
structure elements and the associated page images. The ordinal
page numbers used in document presentation refer to
the PAGE structure elements, and have no relationship
to any page numbers which may be associated with the "logical
pages" of the document.
Information objects in the environment of the Presentation
Process which are used in the presentation of documents are
identified by
Some of these information objects are defined by this
International Standard, whereas others are defined elsewhere.
ASN.1 object identifiers and public identifiers
defined by ISO/IEC 9070 are referred to as Public
Object Identifiers.
This International Standard defines Public Object Identifiers
for the identification of several information objects. For each
such information object, this International Standard specifies
both
which identify that information object.
Each information object for which this International Standard
defines a Public Object Identifier is identified by an
The identification of an information object which is defined
by this International Standard in an instance of SPDL Structure
should use:
The text of this International Standard describes the effect
of several parameter values which are specified by means of a
Public Object Identifiers. In these cases, the parameter value
represented by the Public Object Identifier is represented by
the Object Name corresponding to that Public Object Identifier
in italics, e.g. An information object in the environment of the Presentation
Process may also be identified by an Environment Name. An
Environment Name consists of single object-name component as
defined by ISO/IEC 9070.
An Environment Name is semantically equivalent to
the ISO/IEC 9070 public identifier for which the
owner name is the word "UNREGISTERED" and the object
name consists of a single object-name component. Specifically,
the Environment Name " The SPDL structure is easily parsable by a variety of
processes. These include imposition processes and processes
which extract pages or pictures from SPDL documents as well as
Presentation Processes. To support the parsing of the SPDL
structure by a variety of processes in a variety of
environments, both ASN.1 and SGML
encodings of the SPDL structure are standardized. An SPDL
Presentation Process only needs to be able to process one of the
representations to conform to this International Standard.
The SPDL structure enables processes to extract elements
from SPDL documents together with relevant attributes, and to
determine external resource requirements, without having to
interpret the content elements which specify page and picture
images. No process other than an SPDL Presentation Process needs
to be able to process the content notation.
The SPDL structure specifies the logical structure of an
instance of SPDL. Not every structure element need have an
explicit representation in the Structure Representation and
Interchange Format, so long as the logical structure of each
instance of SPDL is unambiguously represented.
This International Standard specifies two representation and
interchange formats for the encoding of the SPDL structure:
The Binary Structure Representation and Interchange Format is
based on ASN.1. The Clear Text Structure
Representation and Interchange Format is based
on SGML. The Binary Structure Representation and
Interchange Format and the Clear Text Structure Representation
and Interchange Format are fully equivalent: any functionality
that can be expressed in one can be expressed in the other with
a simple syntactic transformation.
The Structure Representation and Interchange Formats ensure
that every instance of SPDL is self-identifying within the
domain of use of the structure notations on which the Structure
Representation and Interchange Formats are based.
This International Standard also specifies two Representation
and Interchange Formats for the encoding of the token sequences
which comprise the content:
For reasons of compactness and efficiency of interpretation,
specialized representations optimized for compactness and ease
of interpretation are used.
The Binary Content Representation and Interchange Format is
used with the Binary Structure Representation and Interchange
Format. The Clear Text Content Representation and Interchange
Format is used with the Clear Text Structure Representation and
Interchange Format.
An instance of the Standard Page Description Language may
represent a document, define or undefine a resource, or
encapsulate a structure element which may be included in another
instance of SPDL by reference.
An Representation and Interchange Format (ASN.1
or SGML). The TOP LEVEL STRUCTURE
structure element is the structure element at the highest
structure level of the SPDL Instance.
An SPDL Instance in the Binary Structure Representation and
Interchange Format shall be encoded as an instance of
the ASN.1 EXTERNAL type for which
An SPDL Instance in the Clear Text Structure Representation
and Interchange Format shall be encoded as an SGML
document instance for which
A TOP LEVEL STRUCTURE structure element shall be
one of:
which is not subordinate to any other structure element.
The Structure Representation and interchange Format allows
for the the inclusion of comments in any instance of SPDL. The
method of including comments in an instance of SPDL Instance
depends on the Structure Representation and Interchange Format
being used. Comments shall have no effect on either structure
processing or content processing.
Comments consist of IA5Strings (as defined
in ISO/IEC 8824) which do not interfere with the
parsing of the chosen Structure Representation and Interchange
Format.
Subordinates and immediate subordinates
Superiors and immediate superiors
Most immediately superior structure elements
Peers
Highest structure level
Document Structure Elements
Scope
Sequential Order
Sequential Order and Hierarchical Structure
Example
Presentation Order
Ordinal Page Number
Pages and Imposition
Identification of Information Objects
Public Object Identifiers
Assignment of Public Object Identifiers
Notation
Environment Names
Representation and Interchange Format
Instances of the Standard Page Description Language
Binary Structure Representation and Interchange
Format
Clear Text Structure Representation and
Interchange Format
TOP LEVEL STRUCTURE
Comments