It is currently not clear what happens if someone were to write the following:

<xsl:variable name="time">
   <xsl:stream href="http://timsrvr/current-time.php">
      <xsl:value-of select="/time/@current-time" />
   </xsl:stream>
</xsl:variable>

Because xsl:stream is non-deterministic and is allowed to return different results when called multiple times, and because it is likely that processors process a variable only once, this construct may not deliver what people might expect.

This is even more apparent with functions and the new cache attribute:

<xsl:function name="f:time" cache="no">
   <xsl:stream href="http://timsrvr/current-time.php">
      <xsl:value-of select="/time/@current-time" />
   </xsl:stream>
</xsl:function>

Because caching is currently a non-mandatory hint, again this might not do what a user expects, and the result may well be different between different processors, or even between invocations of the same processor.

I propose to resolve this by removing cache="no", which may not do what users expect, but instead use cache="default", which leaves it to the processor, and cache="never", which is a mandatory hint to the processor to actually never cache the results.

We could extend this to variables, though that might raise some eyebrows. Or we can leave it as-is for variables (implementation defined), perhaps with an added Note that explicitly says what might happen in such situations.