The DITA specification uses specific notation and terms
to define the components of the DITA standard.
following conventions are used throughout the
- attribute types
- Attribute names may be preceded by @ to distinguish them from
elements or surrounding text, for
example, the @props or the @class
- element types
- Element names may be delimited with angle brackets (< and >)
to distinguish them from surrounding
text, for example, the <keyword>
and the <prolog> element.
In general, the unqualified
use of the term map or topic
can be interpreted to mean "a <map> element and any specialization
of a <map> element " or "a <topic> element
or any specialization of a <topic> element."
Normative and non-normative information
The DITA specification contains normative and non-normative
- Normative information
- Normative information is the formal portion of the specification
that describes the rules and requirements
that make up the DITA standard
and which must be followed.
- Non-normative information
- Non-normative information includes descriptions that provide
background, examples, and other
useful information that are not
formal requirements or rules that must be followed. The terms
non-normative and informative are used
All information in the specification
should be considered normative unless it is an
example, an appendix, or is explicitly labeled as informative or
non-normative. Appendices are always non-normative,
unless explicitly stated otherwise. The DITA specification
contains examples to help clarify or illustrate
specific aspects of the specification. Because examples are specific
rather than general, they may not illustrate all
aspects or be the only way to accomplish or implement
an aspect of the specification. Therefore all examples
are non-normative, unless explicitly stated otherwise.
Basic DITA terminology
The following terminology is used to discuss basic
- DITA attribute type
- An attribute type that is one of the following:
- One of the base attribute types that are defined by the DITA
- A specialization of the either the @base or @props
- DITA document
- An XML document that conforms to the requirements of this
specification. A DITA document must have
as its root element one of the following
- <map> or a specialization of the <map> element
- <topic> or a specialization of the <topic> element
- <dita>, which cannot be specialized, but which allows
documents with multiple sibling
- DITA document type
- A unique set of structural modules, domain modules, and constraint
modules that taken together provide
the XML element and attribute declarations
that define the structure of DITA documents. DITA
document types normally are implemented using DITA document-type
- DITA document-type shell
- A set of DTD or XSD declarations that implement a DITA document
type by using the rules and design patterns
that are included in the DITA specification.
A DITA document-type shell includes and configures one
or more structural modules, zero or more domain
modules, and zero or more constraint
modules. With the exception of the optional
declarations for the <dita> element and its attributes,
DITA document-type shells do not declare
any element or attribute types directly.
- DITA element
- An XML element instance whose type is a DITA element type. DITA
elements must exhibit a @class attribute
that has a value that conforms to the
rules for specialization hierarchy specifications.
- DITA element type
- An element type that is one of the following:
A DITA element type is declared in exactly one vocabulary module.
DITA element types may only exhibit
attributes that are DITA attribute types.
- One of the base element types that are defined by the DITA
- A specialization of one of the base element types
- map instance
- An occurrence of a map type in a document.
- map type
- An element type that defines a set of relationships among topic
instances. The map type provides the
root element and, through the contained
element types, the substructure for the map instances. The
map substructure provides hierarchy, group,
and matrix organization of references
to topic instances.
- structural type instance
- An occurrence of a topic type or a map type in a document.
- topic instance
- An occurrence of a topic type in a document.
- topic type
- An element type that defines a complete unit of content. The topic
type provides the root element for the
topic and, through the contained element
types, the substructure for the topic instances. The root
element of the topic type is not necessarily
the same as the root element of a document
type; document types may nest multiple topic
types and may also declare non-DITA wrapper elements as the
root element for compatibility with
The following terminology is used to discuss DITA
- base content model
- The content model of a DITA element before specialization or the
application of constraints or extensions.
- base type
- An element or attribute type that is not a specialization. All
base types are defined by the DITA specification.
- extension element
- Within a vocabulary module, an element type that can be extended,
replaced, or constrained for use in
a DITA document type.
- The process by which a specialized element is transformed into
a less-specialized ancestor element
or a specialized attribute is transformed
into a less-specialized ancestor attribute. The original
specialization-hierarchy information may be preserved
in the generalized instance, thus allowing
the original specialized type to be
recreated from the generalized instance.
- restricted content model
- For a DITA element type, a content model that has been restricted
from the base content model for the
element type by one or more of
the following mechanisms:
Content models may be restricted through the use of constraint
modules or through specialization.
- Removing optional elements
- Requiring optional elements
- Ordering of unordered elements
- Restricting repeatable (but optional) elements from
- selective domain extension
- An extension that replaces an extension element with element types
that are defined in an domain module,
thus making the base type unavailable
in the DITA document-type shell that configures the extension.
- (1) The act of defining new element or attribute types as a semantic
refinement of existing element or attribute
- (2) An element or attribute type that is a specialization of a
- (3) A process by which a generalized element is transformed into
one of its more specialized element
types or a generalized attribute is
transformed into a more specialized attribute.
- specialization hierarchy
- The sequence of element or attribute types, from the most general
to most specialized, from which a given
element or attribute type is specialized.
The specialization hierarchy for a DITA element is
formally declared through its @class attribute.
- specialization parent
- For a given DITA element type, the most specialized of its ancestors
in its specialization hierarchy.
- specialized attribute type
- An attribute type that is defined as a semantic refinement of
another attribute type. The attribute
type must be specialized from either the
@base or @props attribute, and its range of permissible values
must be a subset of or identical to
the values allowed by the original attribute
- specialized element type
- An element type that is defined as a semantic refinement of an
existing element type. The content allowed
by the specialized element type must
be a subset of or identical to the content allowed by the original
element type. Within a DITA document,
all specialized element types must be
refinements of one of the base element types, with the
exception of elements that are used in the context
of <foreign> or <unknown> elements.
- structural type
- A topic type or map type.
The following terminology is used to discuss DITA modules:
- attribute domain module
- A domain module that defines exactly one specialization of either
the @base or @props attribute.
- constraint module
- A set of declarations that imposes additional constraints onto
the element or attribute types that
are defined in a specific vocabulary
- domain module
- A set of element types or an attribute type that supports a specific
subject or functional area. Element
types or attribute types in a domain
can be integrated with topic types or map types to enhance
semantic support for particular kinds of content.
For example, the structural type <topic>
declares the <keyword> element; when
integrated with a domain for describing user interfaces, new keyword
specializations (such as <wintitle>)
become available wherever <keyword>
was allowed in the original structural type.
- element domain module
- A domain module that defines one or more element types for use
within maps or topics.
- map module
- A structural module that defines a single map type.
- structural module
- A vocabulary module that defines exactly one top-level map type
or topic type. Structural modules may also
define specializations of elements from
- topic module
- A structural module that defines a single top-level topic type.
- vocabulary module
- A uniquely-named unit of element type or attribute type declaration.
There are two types of vocabulary modules:
structural modules and domain modules.
For a given map type, topic type, or domain, there is
exactly one vocabulary module that defines it.
The following figure illustrates
the relationship between a DITA document, its
DITA document-type shell, and the various vocabulary modules that
Figure 1. Instances, modules, and declarations
Linking and addressing terms
The following terminology is used to discuss linking
and addressing terms:
- key name
- An identifier defined by a value of the @keys
attribute. A key is bound to one or more
of the following items:
- A resource addressed by the <topicref> element or a
specialization of the <topicref>
- An element contained with the <topicmeta> element of the
<topicref> element or a specialization
of the<topicref> element
- key definition
- A <topicref> element or specialization of a <topicref> element
that specifies the @keys attribute and
defines one or more key names.
- key resolution context
- The root map that establishes the context for resolving key references.
For a given key-resolution instance,
there is at most one root map that defines
the effective value of the key space, as determined by
the key definition precedence rules..
- key space
- The effective set of unique key names that are defined by a given
key resolution context. Within a given
key resolution context, a key name has
at most one binding.
- referenced element
- An element that is referenced by another DITA element. See also referencing
The following code sample is from the
The <step> element that it contains
is a referenced element; other
DITA topics reference the <step> element by using the @conref
<cmd>Run the startcmd script that is applicable to your operating-system environment.</cmd>
- referencing element
- An element that references another DITA element by specifying
an addressing attribute. See also referenced
element and addressing attribute
The following <step> element is a referencing
element. It uses the @conref attribute
to reference a <step> element
in the installation-reuse.dita
- addressing attribute
- An attribute, such as @conref, @conkeyref, @keyref, and @href,
that specifies an address (a URI reference
or a key reference).