That is not conformant behaviour.

If your output method is HTML and the element type is an HTML element type, then that *is* the expected output because in that case SGML conventions are used, but otherwise a conforming processor would put out the following XML conventions for the default XML output method:

Please check your <xsl:output/> instruction for the use of HTML ... but your report is not at all consistent with my expectations of MSXML and Xalan, both of which should be producing a properly constructed empty element.

If you think you are engaging everything properly, then please post a short (15 line?) complete stylesheet that illustrates your results so that others can run your stylesheet on their system.

I hope this helps.