@format attribute identifies the format of
the resource that is referenced.
If no value is
specified, but the attribute is specified on an ancestor
within a map or within the related-links section, the value
will cascade from the closest ancestor.
The following values for
@format have special processing
- The destination uses DITA topic markup or markup specialized from
a DITA topic. Unless otherwise specified, when
@formatis set to "dita", the value for the
@typeattribute will be treated as "topic".
- The linked-to resource is a DITA map. It represents the referenced
hierarchy at the current point in the referencing map.
References to other maps can occur at any point in a map, but
because relationship tables are only valid as children of a map,
referenced relationship tables are treated as children of the
referencing map. Note: If a
<topicref>element that references a map contains child
<topicref>elements, the processing behavior regarding the child
<topicref>elements is undefined.
- (no value)
- The processing default is used. The
processing default for the
@formatattribute is determined by inspecting the value of the
@hrefattribute. If the
@hrefattribute specifies a file extension, the processing default for the
@formatattribute is that extension, after conversion to lower-case and with no leading period. The only exception to this is if the extension is "xml", in which case the default format is "dita". If there is no extension, but the
@hrefvalue is an absolute URI whose scheme is "http" or "https", then the processing default is "html". In all other cases where no extension is available, the processing default is "dita".
If the actual format of the referenced content differs from the effective value of the
@formatattribute, and a processor is capable of identifying such cases, it MAY recover gracefully and treat the content as its actual format, but SHOULD also issue a message.
For other formats, using the file extension without the "." character
typically represents the format. For example, the following values are
all possible values for
- The format of the linked-to resource is HTML or XHTML.
- The format of the linked-to resource is PDF.
- The format of the linked-to resource is a text file.