A quick research on how other sch editors do this:
<ul>
	<li> gschem/lepton: filled circle/rectangle
	<li> orcad: similar to gschem
	<li> kicad: circle
	<li> eagle: none
	<li> altium: none
</ul>
<p>
(Youtube tutorial videos are good source on such research.)
<p>
It seems both indication and no indication are accepted by users and
there is no uiversally accepted style of inidication.