Icon Set category

I am trying to set my own category in a .dis file if I use this it does not create a category

<?xml version="1.0" encoding="UTF-8"?>
<iconset name="DOpus-NoSmiley">
	<display_name>NoSmiley - Override smiley icon with sad red smiley</display_name>
	<copyright>none</copyright>
	<artist>tbone</artist>
	<set filename="smallred.png" height="20" size="small" width="20"  category="MRD" >
		<icon col="1" name="smiley" row="1" />
	</set>
</iconset>

If I use this it does

<?xml version="1.0" encoding="UTF-8"?>
<iconset name="DOpus-NoSmiley">
	<display_name>NoSmiley - Override smiley icon with sad red smiley</display_name>
	<copyright>none</copyright>
	<artist>tbone</artist>
	<set filename="smallred.png" height="20" size="small" width="20" >
		<icon col="1" name="smiley" row="1"  category="MRD" />
	</set>
</iconset>

Looks like the documentation is wrong. The first version would be like this:

<?xml version="1.0" encoding="UTF-8"?>
<iconset name="DOpus-NoSmiley">
	<display_name>NoSmiley - Override smiley icon with sad red smiley</display_name>
	<copyright>none</copyright>
	<artist>tbone</artist>
	<set filename="smallred.png" height="20" size="small" width="20">
		<category name="MRD">
			<icon col="1" name="smiley" row="1" />
		</category>
	</set>
</iconset>