Can use both ''' and '"' to quote an attribute value.
<element attribute="value"/> or <element attribute='value'/>
An XML Processor will replace all whitespace characters with a space character '#x20'.
If the attribute type is not CDATA, then the XML processor MUST further process the normalized attribute value by discarding any leading and trailing space (#x20) characters, and by replacing sequences of space (#x20) characters by a single space (#x20) character.
All attributes for which no declaration has been read SHOULD be treated by a non-validating processor as if declared CDATA.