[_ck_]

Well you’d have to use an existing html tag like blockquote and map it to a bbcode tag via another plugin.

But blockquote can have made-up attributes.

ie.

<blockquote post="1824" author="_ck_">blah blah</blockquote>

But it’s much more simple to start with non-intelligent quoting. You can place the post reference but to look for it and analyse it is much more difficult.

Stripping nested blockquotes will be very easy.

Well fairly easy.