<reltable>
The <reltable>
element is a relationship table that specifies
relationships among topics, based on the familiar table model of rows
(<relrow>
), columns (<relheader>
), and cells
(<relcell>
).
A frequently-used type of relationship table establishes relationships between task, concept, and reference topics. Each column in a relationship table typically represents a specific role in a set of relationships; for example, the first column often contains references to tasks, while the second and third columns often reference concept and reference topics. The relationship table rows define relationships between the resources referenced in different cells of the same row; in this example, each row establishes relationships between tasks and the concept and reference topics that support the tasks. When used in this manner, relationship tables make it easy to determine where related information is missing or undefined.
By default, the contents of a <reltable>
element are not output for navigation or TOC purposes; they are used
only to define relationships that can be expressed as topic-to-topic
links. The <relcell>
elements can contain <topicref>
elements, which are then related to other <topicref>
elements in the same row (although not necessarily in the same cell).
Relationship tables can be used in conjunction with hierarchies and groups to manage all the related links in an information set.
Within a map tree, the effective relationship table is the union of all relationship tables in the map.
See appendix for information about this element in OASIS document type shells.
- map/reltable
In this example, a relationship table is defined with three columns; one for "concept", one for "task", and one for "reference". Three cells are defined within one row. The first cell contains one concept topic: batsonar.dita. The second cell contains two task topics: batcaring.dita and batfeeding.dita. The third cell contains two reference topics: batguano.dita and bathistory.dita.
<map>
<reltable>
<relheader>
<relcolspec type="concept"/>
<relcolspec type="task"/>
<relcolspec type="reference"/>
</relheader>
<relrow>
<relcell>
<topicref href="batsonar.dita"/>
</relcell>
<relcell>
<topicref href="batcaring.dita"/>
<topicref href="batfeeding.dita"/>
</relcell>
<relcell>
<topicref href="batguano.dita"/>
<topicref href="bathistory.dita"/>
</relcell>
</relrow>
</reltable>
</map>
A DITA-aware tool might represent the
<reltable>
element graphically:
type="concept" | type="task" | type="reference" |
---|---|---|
batsonar.dita | batcaring.dita |
batguano.dita |
On output, links should be added to topics that are in the same row, but not in the same cell.
This allows simple maintenance of parallel relationships: for example, in this case,
batcaring.dita and batfeeding.dita are two tasks
that require the same supporting information (concept and reference topics) but might
otherwise be unrelated. When topics in the same cell are in fact related, the cell's
@collection-type
attribute can be set to family. If some cells or columns
are intended solely as supporting information and should not link back to topics in other
cells, you can set the @linking
attribute on the
<relcell>
or <relcolspec>
to
"targetonly".
Although such tables can initially take some time to learn and manipulate, they are inherently an efficient way to manage these links. In particular, they increase the prospect for reuse among topics, because those topics do not contain context-specific links. A relationship table also makes it easy to see and manage patterns; for example, the fact that batfeeding.dita and batcaring.dita have the same relationships to supporting information is clear from the table, but would require some comparison and counting to determine from the list summary just before this paragraph.
The following attributes are available on this element: Universal attribute group, Attributes common to many map elements (without the @keyscope
attribute, and with a narrowed definition of
@toc
, given below), outputclass, and the attributes defined
below. This element also uses @type
, @scope
, and
@format
from Link relationship attribute group.
@toc
@toc
is "no". See Attributes common to many map elements for a complete definition of
@toc
.@title