the meaning of lax

Hej,

in schema spec 1.1 'lax' is defined as

	If the item has a uniquely determined declaration available, it must be ·valid· with respect to that definition,
        that is, ·validate· if you can, don't worry if you can't.

I don't know if it is just me as a non-native speaker, but somehow that sentence confuses me...
Let's say there is an element that matches a wildcard that has processContents 'lax'.

1) if I find a declaration for that element and

	a) can validate it successfully -> everything ok

	b) can not validate it successfully -> ?!?

2) if I cannot find a declaration for that element

	-> everything ok

What happens in case a 1b? Could the sentence in the spec maybe rephrased?

Ciao,
Tobias