Hi Mark,

> ...OK, that's clear, but what is the '@' sign
> used for? For instance, at the top of page 237:
> <xsl:if test="@rating > $minRating">

@ is short for attribute::

> Are there other such symbols and where do I find them defined?

I cannot imagine that Jeni Tennison has not described these in detail
in her book.
But otherwise, you can find them on Mulberrytech's quick reference:
http://www.mulberrytech.com/quickref/XSLT_1quickref-v2.pdf

Hope this helps,
Ragulf Pickaxe :-)