Saxon

It's a tricky one, because

(a) We don't want to default to being "schema-aware" just because the user is running EE with a license, because unless they've written the stylesheet code to benefit from schema-awareness, this gives costs and no benefits (when running schema-aware with no schema, we have no idea what the static type of @someAttr is, for example, whereas when running schema-unaware, we know it will be xs:untypedAtomic).

(b) If we encounter an xsl:import-schema declaration, it seems much more helpful to switch schema-awareness on at that point rather than tell the user that the declaration isn't allowed because the processor isn't schema-aware.

(c) But we process static expressions during the initial parse of the stylesheet, so there is no opportunity to look ahead to see if there is going to be an xsl:import-schema declaration.

One solution might be to commit to a decision on schema-awareness the first time the question comes up, and then stick to it. So if there's a call on system-property('is-schema-aware'), then if nothing has been said in advance, we make a decision at this point: typically "yes" if we're running EE with a license (and not with target="JS"), "no" otherwise. This is on the assumption that if the user is asking the question, they have written code that will benefit from the answer being "yes"; it also better reflects the W3C approach that schema-awareness is a property of the "processor".