<preserveSpace
  elements = list of XPath (subset)
/>

Specifies which elements are whitespace-preserving.

Using standard attribute xml:space with default value preserve is still the preferred way of specifying this. However, this is not always possible, for example in the case of DTDs/ W3C XML schema that you don't control or in the case of RELAX NG schema which do not really support the concept of attribute default value.

DocBook example:

<cfg:preserveSpace xmlns="" 
    elements="address funcsynopsisinfo classsynopsisinfo 
              literallayout programlisting screen synopsis" />