Cascading of attributes from map to map

Certain elements cascade from map to map, although some of the attributes that cascade within a map do not cascade from map to map.

The following attributes cascade from map to map:

@audience, @platform, @product, @otherprops, @rev
@props and any attribute specialized from @props
@linking, @toc, @print, @search
@type
@translate
@processing-role
@cascade

Note that the above list excludes the following attributes:

@format: The @format attribute must be set to "ditamap" in order to reference a map or a branch of a map, so it cannot cascade through to the referenced map.
@xml:lang and @dir: Cascading behavior for @xml:lang is defined in The xml:lang attribute. The @dir attribute work the same way.
@scope: The value of the @scope attribute describes the map itself, rather than the content. When the @scope attribute is set to "external", it indicates that the referenced map itself is external and unavailable, so the value cannot cascade into that referenced map.

The @class attribute is used to determine the processing roles that cascade from map to map. See Cascading of roles from map to map for more information.

As with values that cascade within a map, the cascading is additive if the attribute permits multiple values (such as @audience). When the attribute only permits one value, the cascading value overrides the top-level element.

Example of attributes cascading between maps

For example, assume the following references in test.ditamap:

<map>
  <topicref href="a.ditamap" format="ditamap" toc="no"/>
  <mapref   href="b.ditamap" audience="developer"/>
  <topicref href="c.ditamap#branch1" format="ditamap" print="no"/>
  <mapref   href="c.ditamap#branch2" platform="myPlatform"/>
</map>

The map a.ditamap is treated as if toc="no" is specified on the root <map> element. This means that the topics that are referenced by a.ditamap do not appear in the navigation generated by test.ditamap (except for branches within the map that explicitly set toc="yes").
The map b.ditamap is treated as if audience="developer" is set on the root <map> element. If the @audience attribute is already set on the root <map> element within b.ditamap, the value "developer" is added to any existing values.
The element with id="branch1" within the map c.ditamap is treated as if print="no" is specified on that element. This means that the topics within the branch with id="branch1" do not appear in the printed output generated by test.ditamap (except for nested branches within that branch that explicitly set print="yes").
The element with id="branch2" within the map c.ditamap is treated as if platform="myPlatform" is specified on that element. If the @platform attribute is already specified on the element with id="branch", the value "myPlatform" is added to existing values.