Example: How the cascade attribute functions

Darwin Information Typing Architecture (DITA) Version 1.3 Part 1: Base Edition

version
1.3
author
OASIS DITA Technical Committee

The following example illustrates how the cascade attribute can be used to fine tune how the values for the platform attribute apply to topics referenced in a DITA map.

Here a DITA map contains a collection of topics that apply to Windows, Linux, and Macintosh OS; it also contains a topic that is only applicable to users running the application on Linux.

<map product="PuffinTracker" platform="win linux mac" cascade="nomerge">
  <title>Puffin Tracking Software</title>
  <topicref href="intro.dita" navtitle="Introduction"/>
  <topicref href="setup.dita" navtitle="Setting up the product"/>
  <topicref href="linux-instructions.dita" navtitle="Linux instructions" platform="linux"/>
</map>

The values of the platform attribute set at the map level cascade throughout the map and apply to the "Introduction" and "Setting up the product" topics. However, since the value of the cascade attribute is set to "nomerge", the value of the platform attribute for the "Linux instructions" topic does not merge with the values that cascade from above in the DITA map. The effective value of the platform attribute for linux-instructions.dita is "linux".

The same results are produced by the following mark-up:

<map product="PuffinTracker" platform="win linux mac">
  <title>Puffin Tracking Software</title>
  <topicref href="intro.dita" navtitle="Introduction"/>
  <topicref href="setup.dita" navtitle="Setting up the product"/>
  <topicref href="linux-instructions.dita" navtitle="Linux instructions" platform="linux" cascade="nomerge"/>
</map>