[xsl] XSLT 1.0/2.0 forward/backwards compatibility behavior

[Frans Englich <frans.englich@xxxxxxxxx>]

Hi,

I'm a bit confused with backwards/forwards compatibility between XSLT 1.0/2.0.
Here's what I've concluded:

An XSLT 2.0 processor running in backwards compatibility mode(due to
xsl:version=1.0) accepts an illegal XSLT 1.0 stylesheet, as long as it is
valid XSLT 2.0(say, an if statement was in an expression). Hence, one can
write an "1.0" stylesheet which works just fine with an XSLT 2.0 processor,
but is flagged as invalid at a static stage with an XSLT 1.0 processor.

I think this is right, because Saxon confirms it, and it is how I interpret
the specifications.

What makes me wonder is because I find it hard to to motivate this behavior or
see it in a practical perspective.