PR for white spaces

Hi David, all,

In the white spaces section we have this PR:

"For the elements <sc>, <ec>, <ph> and <data>: The white spaces of their content MUST be preserved in all cases, even if the value
for xml:space is set or inherited as default."

<sc>, <ec> and <ph> are empty elements and therefore cannot have content, so we shouldn't list them here. Only <data> should be
listed here.

Cheers,
-yves