Chapter 3, Section 4.2.6. The conrefend attribute

4.2.6. The conrefend attribute

The conrefend attribute is used when referencing a range of elements with the conref mechanism. The conref or conkeyref attribute points to the first element in the range, while conrefend points to the last element in the range. Although the start and end elements must be of the same type as the referencing element (or specialized from that element), the intermediary, contiguous nodes in the middle of the range do not have to be the same.

Using conref together with conrefend

Several items must be taken into account when using or implementing conrefend.

Processors will resolve the range by pulling in the start target and following sibling DOM nodes across to and including the end target.
The start and end elements of a range must be of the same type as the referencing element, or they must be generalizable to the referencing element. For example, conref and conrefend may point from <li> to other <li> elements, or to specializations of <li> such as <step>.
As with conref, if the conrefend points to a more specialized version of the referencing element, applications should generalize the target when resolving.
It is not valid to use conrefend to point to a more general version of an element (such as using step to reference an li element).
Other nodes (such as elements or text) between the start and end of a range do not have to match the referencing element.
The start and end elements in a range must share the same parent.
The parent of the referencing element must be the same as the parent of the target range, OR the parent of the target range may be a specialized version of the reference's parent. For example, it is possible to pull a range from conbody into body, because conbody is specialized from body. It is not possible to pull a range from body into conbody, because the result may not be valid in conbody.
With single conref, an id attribute from the target will not be preserved on the resolved content. With a range, an id on both the start and the end will not be preserved. Id attributes on intermediate or child nodes should be preserved, although if this results in duplicate id values, an application may or may not recover by changing the id or by warning the user.
With a single conref, attributes specified locally may be used to override attributes on the referenced content. With a conref range, the same is true, with the following clarifications:
- When an id attribute is specified on the referencing element, it will only be preserved on the first element of the resolved range.
- When other attributes are specified, they will only apply to referenced elements of the same type. For example, if <step> is used to pull in a range of sequential step elements, locally specified attributes apply to all steps in the range. If <ol> is used to pull in a series of (ol, p, ol), locally specified attributes apply only to the <ol> elements in that range.

Example: reusing a set of list items

Figure 3-65. List example: Source topic.dita with ids

<topic id="x">
 	...
 	<body>
 		<ol>
 			<li id="apple">A</li>
 			<li id="bear">B</li>
 			<li id="cat">C</li>
 			<li id="dog">D</li>
 			<li id="eel">E</li>
 		</ol>
 	</body>
 </topic>

Figure 3-66. List example: Reusing topic with conrefs

 <topic id="y">
 	...
 	<body>
 		<ol>
 			<li>My own first item</li>
 			<li conref="topic.dita#x/bear" conrefend="topic.dita#x/dog"/>
 			<li>And a different final item</li>
 		</ol>
 	</body>
 </topic>

Figure 3-67. List example: Processed result of reusing topic

 <topic id="y">
 	...
 	<body>
 		<ol>
 			<li>My own first item</li>
 			<li>B</li>
 			<li id="cat">C</li>
 			<li>D</li>
 			<li>And a different final item</li>
 		</ol>
 	</body>
</topic>

Example: Reusing a set of blocks

Figure 3-68. Block level example: Source topic.dita with ids

<topic id="x">
 	...
 	<body>
   <p id="p1">First para</p>
 	 <ol id="mylist">
     <li id="apple">A</li>
     <li id="bear">B</li>
     <li id="cat">C</li>
     <li id="dog">D</li>
     <li id="eel">E</li>
   </ol>
   <p id="p2">Second para</p>
 	</body>
 </topic>

Figure 3-69. Block level example: Reusing topic with conrefs

 <topic id="y">
 	...
 	<body>
 		<p conref="topic.dita#x/p1" conrefend="topic.dita#x/p2"/>
 	</body>
 </topic>

Figure 3-70. Block level example: Processed result of reusing topic

 <topic id="y">
 	...
 	<body>
    <p>First para</p>
 	  <ol id="mylist">
      <li id="apple">A</li>
      <li id="bear">B</li>
      <li id="cat">C</li>
      <li id="dog">D</li>
      <li id="eel">E</li>
    </ol>
    <p>Second para</p>
 	</body>
</topic>

Using conrefend together with conkeyref

When the conkeyref attribute is used in place of conref, a key is used to address the target of the reference. The conrefend attribute, which indicates the end of a conref range, may not use a key. Instead the the map or topic element addressed by the key name component of the conkeyref is used in place of whatever map or topic element is addressed by the conrefend attribute.

For example, if the value of the conkeyref attribute is "config/step1" and the value of the conrefend is "defaultconfig.dita#config/laststep", the conref range will end with the step that has id="laststep" in whatever topic is addressed by the key name "config". If the key name "config" is not defined, and the conref attribute itself is not present for fallback, the conrefend attribute is ignored.

Example: Combining conrefend with conkeyref

Figure 3-71. Defining and referencing a key with conkeyref

In this example the key "xmp" is defined as the first topic in the file examples.dita.

<map>
  <!-- ... -->
  <keydef keys="xmp" href="examples.dita"/>
  <!-- ... -->
</map>

examples.dita:
<topic id="examples">
  <title>These are examples</title>
  <body>
    <ul>
      <li id="first">A first example</li>
      <li>Another trivial example</li>
      <li id="last">Final example</li>
    </ul>
  </body>
</topic>

To reuse these list items by using the key, the conkeyref attribute combines the key itself with the sub-topic id (first) to define the start of the range. The conrefend attribute defines a default high-level object along with the sub-topic id (last) that ends the range:

  <li conkeyref="xmp/first" 
      conrefend="default.dita#default/last"/>

The conkeyref attribute uses a key to reference the first topic in examples.dita, so the range begins with the object examples.dita#examples/first. The high-level object in the conrefend attribute (default.dita#default) is replaced with the object represented by the key (the first topic in examples.dita), resulting in a range that ends with the object examples.dita#examples/last.

Figure 3-72. Combining conref, conkeyref, and conrefend

When conref, conkeyref, and conrefend are all specified, the key value takes priority.

  <li conkeyref="thisconfig/start"
      conref="standardconfig.dita#config/start"
      conrefend="standardconfig.dita#config/end"/>

If the key "thisconfig" is defined as mySpecialConfig.dita#myconfig, then the range will go from the list item with id="start" to the list item with id="end" in the topic mySpecialConfig.dita#myconfig.
If the key "thisconfig" is defined as myConfig.dita, then the range will go from the list item with id="start" to the list item with id="end" within the first topic in myConfig.dita.
If the key "thisconfig" is not defined, then the unchanged conref and conrefend attributes are used as fallback. In that case, the range will go from the list item with id="start" to the list item with id="end" within the topic standardconfig.dita#config.

Error conditions

When encountering an error condition, an implementation may but need not issue an error message.

Condition or Issue	Result
The conref attribute cannot be resolved in the target document (the target element may have been removed or its ids has changed).	The conref is ignored.
The conrefend attribute cannot be resolved in the target document (the target element may have been removed or its id has changed).	Range cannot be resolved, optional recovery processes the result as a simple conref.
Start and end elements are not siblings in the target document.	If the start element exists, optional recovery processes the result as a simple conref.
End element occurs before the start element in the target document.	If the start element exists, optional recovery processes the result as a simple conref.
An element has a conrefend attribute but is missing the conref	No result.

‣ Parent topic: Section 4.2. Complex attribute definitions

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