libxml2 tree: NULL vs empty string

In libxml2, C calls

xmlNewPI("name", NULL);
xmlNewPI("name", "");

produce the following processing instructions

<?name?>
<?name ?>

(notice the space in the second case). At the first moment I though that I shouldn't allow the first variant. But then reminded that in XML absence of node and empty node are sometimes very different things. So let both variants be.

Then I tested two variants for another node type:

xmlNewComment(NULL);
xmlNewComment("");

The second case produced the expected result

<---->

but the first variant seems broken. In serialized XML, I have no comments at all!

Anyway, I decided to have difference between nothing and empty string. I feel it can be used somehow,

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Categories: Generative XML