XML: xml:space preserve
Meaning of xml:space preserve
the xml:space="preserve"
in XML is fairly complicated.
You cannot just delete it. But also, browsers may not support it.
A whitespace node in XML is a node that's all whitespace. 〔see JS DOM: Whitespace Nodes〕
here's a example:
<p>I <b>love</b> <b>cats</b>.</p>
There is only ONE whitespace node above. It happens between the b tags.
Reference

- Understanding xml:space
- By Jesper Tverskov.
- http://www.xmlplease.com/xml/xmlspace/