xhtml_conform-12 (When the 'xml:space' attribute is not set to 'preserve', then) Leading and trailing white space inside a block element must be removed.
xhtml_conform-13 (When the 'xml:space' attribute is not set to 'preserve', then) LINE FEED characters must be converted into one of the following characters: a SPACE character, a ZERO WIDTH SPACE character (​), or no character (i.e. removed).
xhtml_conform-14 (When the 'xml:space' attribute is not set to 'preserve', then) A sequence of white space characters without any LINE FEED characters must be reduced to a single SPACE character.
xhtml_conform-15 (When the 'xml:space' attribute is not set to 'preserve', then) A sequence of white space characters with one or more LINE FEED characters must be reduced in the same way as a single LINE FEED character.
Tests for assertions xhtml_conform-12, xhtml_conform-13, xhtml_conform-14, xhtml_conform-15

xhtml_conform-12: leading and trailing space in paragraph removed

xhtm_conform-13: LINE FEED characters must be converted into one of the following characters: a SPACE character, a ZERO WIDTH SPACE character (​), or no character (i.e. removed).

xhtml_conform-14: A sequence of white space characters without any LINE FEED characters must be reduced to a single SPACE character.

xhtml_conform-15: A sequence of white space characters with one or more LINE FEED characters must be reduced in the same way as a single LINE FEED character.