View source for Template:~targ

{{#if:{{{1|}}}|{{{1|}}}|{{{2|}}}}}<noinclude>
==Purpose==
If we write {{C|<nowiki>{{{1|{{{2|}}}}}}</nowiki>}} this becomes 2 only if 1 is completely absent, if we call this template as {{C|1=<nowiki>...|1=|2=stuff}}</nowiki>}} then this will become "" (empty string) as {{C|1}} is set, it's just empty. 

In this case you would use:
* {{C|1=<nowiki>{{~targ|1={{{1|}}}|2={{{2|}}}}}</nowiki>}} which evaluates to its 2nd input if 1 is empty
</noinclude>