2.4.3 The extension Element

This is a general-purpose “extension” element. Readers that don’t understand a given extension should be able to safely ignore it. The attributes on this element, and their meanings, vary based on the context. Each known usage is described separately below. The current extensions use attributes exclusively, without any nested elements.

container Parent Element

extension[container_extension] :combinedFootnotes=(true) => EMPTY

With container as its parent element, extension has the following attributes.

Attribute: combinedFootnotes ¶

Always set to true in the corpus.

sourceVariable and derivedVariable Parent Element

extension[variable_extension] :from :helpId => EMPTY

With sourceVariable or derivedVariable as its parent element, extension has the following attributes. A given parent element often contains several extension elements that specify the meaning of the source data’s variables or sources, e.g.

<extension from="0" helpId="corrected_model"/>
<extension from="3" helpId="error"/>
<extension from="4" helpId="total_9"/>
<extension from="5" helpId="corrected_total"/>

More commonly they are less helpful, e.g.

<extension from="0" helpId="notes"/>
<extension from="1" helpId="notes"/>
<extension from="2" helpId="notes"/>
<extension from="5" helpId="notes"/>
<extension from="6" helpId="notes"/>
<extension from="7" helpId="notes"/>
<extension from="8" helpId="notes"/>
<extension from="12" helpId="notes"/>
<extension from="13" helpId="no_help"/>
<extension from="14" helpId="notes"/>

Attribute: from ¶

An integer or a name like “dimension0”.

Attribute: helpId ¶

An identifier.