he examples you have given,
&gt; but it does not always hold.  It is quite common to see
&gt; a pattern of the sort:
&gt; 
&gt; "&lt;x, y&gt;"               denotes x in the real world or
&gt; "&lt;a, b, c, d, e, f&gt;"   denotes a in the real world

I do not think that I would call it "quite common to see",
and although I believe that I may have run across a few
expressions that appear, from a certain angle, distance,
or perspective to look roughly or superfically similar
to these, I tend to suspect that t