ANSI/NISO Z39.96-2015

10 Article Authoring Tag Set, version 1.1 • 10.5 Attributes

10.5.122 @xml:space Space

When printing or displaying the associated element, all white space (such as tabs, ordinary spaces, and line breaks) should be preserved.

In elements <code>, <glyph-data>, and <preformat>, this attribute must have the value preserve (as given below).
Value Meaning
preserve White space should be preserved. (This value is fixed and cannot be changed in a document.).