Directives should be preserved.
*** Parameters: ***
{}
*** Markdown input: ***

<? noTarget?>
<?php ?>
<?xml ?>
<?mrk ?>

Targets <? noTarget?> <?php ?> <?xml ?> <?mrk ?> !

Inside: <?mrk puts "Inside: Hello" ?> last


*** Output of inspect ***
md_el(:document,[
	md_el(:xml_instr,[],{:code=>" noTarget",:target=>""},[]),
	md_el(:xml_instr,[],{:code=>"",:target=>"php"},[]),
	md_el(:xml_instr,[],{:code=>"",:target=>"xml"},[]),
	md_el(:xml_instr,[],{:code=>"",:target=>"mrk"},[]),
	md_par([
		"Targets ",
		md_el(:xml_instr,[],{:code=>"noTarget",:target=>""},[]),
		" ",
		md_el(:xml_instr,[],{:code=>"",:target=>"php"},[]),
		" ",
		md_el(:xml_instr,[],{:code=>"",:target=>"xml"},[]),
		" ",
		md_el(:xml_instr,[],{:code=>"",:target=>"mrk"},[]),
    " !"
	]),
	md_par([
		"Inside: ",
		md_el(:xml_instr,[],{:code=>"puts \"Inside: Hello\"",:target=>"mrk"},[]),
		" last"
	])
],{},[])
*** Output of to_html ***
&lt;? noTarget?&gt;<?php ?><?xml ?><?mrk ?>
<p>Targets &lt;?noTarget?&gt; <?php ?> <?xml ?> <?mrk ?> !</p>

<p>Inside: <?mrk puts "Inside: Hello"?> last</p>
*** Output of to_latex ***
Targets     !

Inside:  last
*** Output of to_md ***
Targets

Inside: last
*** Output of to_s ***
Targets    Inside:  last