XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (382 page)

Let's look at a simple example where both operands are axis steps: the expression
child::book/attribute::isbn
. (I'm deliberately using the verbose syntax here, the abbreviated form is
book/@isbn
.) So
E1
in this example is the expression
child::book
, which selects all the elements that are children of the context node and have the name
book
. It's possible that the context node doesn't have any

children, of course, in which case this will give you an empty sequence, and when that happens, the result of
E1/E2
is also an empty sequence. But let's suppose it selects three books. For each one of these

elements, the
E2
expression (in our case
attribute::isbn
) is evaluated, with that

as the context node. The step expression
attribute::isbn