Thanks sonichero, that makes sense, but when used as shown below it stops the default signatures from showing even though I have
Show Signatures checked in the my user CP.
PHP Code:
<if condition="$show['signature']">
<!-- sig -->
<div>
__________________<br />
<if condition="$post[signature]">$post[signature]
<else />
DEFAULT SIG HERE
</if>
</div>
<!-- / sig -->
</if>