[Sayid]

<if condition="(THIS_SCRIPT == showthread) OR (THIS_SCRIPT == printthread)">
<link rel="canonical" href="$vboptions[bburl]/showthread.php?t=$threadinfo[threadid]<if condition="$pagenumber>1">&page=$pagenumber</if>" />
</if>
<if condition="(THIS_SCRIPT == showpost)">
<link rel="canonical" href="$vboptions[bburl]/showpost.php?p=$postinfo[postid]"/>
</if>
<if condition="THIS_SCRIPT == index">
<link rel="canonical" href="$vboptions[bburl]" />
</if>

I modify the code to make it work with showpost tempelate

For example, the canonical link for :

showpost.php?p=20020&postcount=18

is:

showpost.php?p=20020

which shows the same single post page but without post count #42 below the tread title

Is it good or not ?