It's certainly not allowed at the moment:

 [ERR XTSE1660]  A basic XSLT processor  must signal a static error if the
stylesheet includes an [xsl:]type attribute, or an [xsl:]validation or
default-validation attribute with a value other than strip.

But it seems a reasonable idea. Raise it on the W3C bugzilla.

Michael Kay
http://www.saxonica.com/ 

> -----Original Message-----
> From: Andrew Welch [mailto:andrew.j.welch@xxxxxxxxx] 
> Sent: 13 November 2008 15:56
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  basic processors handling validation lax
> 
> Would it be wrong for a basic processor to handle (more 
> specifically, not complain about) validation = "lax" ?  This 
> would make it slightly easier to write transforms that run in 
> both basic and schema-aware processors.
> 
> For example, then you could do:
> 
> <xsl:import-schema ....
> use-when="system-property('xsl:is-schema-aware')='yes'"/>
> 
> <xsl:document validation="lax">  (or collection(.... ?validation=lax)
> 
> <xsl:result-document validation="lax">
> 
> ...and run it using a basic processor.  At the moment, the 
> basic processor (Saxon in this case) will state that you need 
> a schema-aware processor to use the validation attribute - 
> but when its set to "lax"
> it should be fine and just operate as if no schema definition 
> is available.
> 
> As it stands, you need to double up and use use-when a lot, 
> but I think it should be possible to set everything to lax 
> and just put use-when on the import-schema elements.
> 
> The benefit would be a simple way of developing/testing with 
> schema-awareness and running without it, or passing around a 
> stylesheet without the need to pass around the schemas with 
> it (both of which depend on the behaviour of the stylesheet 
> not changing on whether the input is typed or not).
> 
> 
> 
> --
> Andrew Welch
> http://andrewjwelch.com
> Kernow: http://kernowforsaxon.sf.net/