Axis order and variables

Hello, friends.

Consider the following XML

  <x n="1">
    <x n="2">
      <test/>
    </x>
  </x>

and transform it via the following XSLT:

  <xsl:transform version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <xsl:output method="text" encoding="UTF-8"/>

    <xsl:template match="/">
      <xsl:for-each select="//test">
        <xsl:variable name="x" select="ancestor::x"/>
        <xsl:value-of select="$x[1]/@n"/>
      </xsl:for-each>
    </xsl:template>

  </xsl:transform>

What is the expected result? Is it "1" or "2"?

I failed to find a definite answer in W3C specs.
Here are some quotes:

  > XML Path Language (XPath) Version 1.0
  >
  >   1 Introduction
  >
  >   [...] An expression is evaluated to yield an object,
  >   which has one of the following four basic types: node-set
  >   (an unordered collection of nodes without duplicates) [...]
  >   The value of a variable is an object, which can be
  >   of any of the types that are possible for the value
  >   of an expression [...]
  >
  >   2.4 Predicates
  >
  >   [...] Thus, the ancestor, ancestor-or-self, preceding,
  >   and preceding-sibling axes are reverse axes [...]
  >   The proximity position of a member of a node-set
  >   with respect to an axis is defined to be the position
  >   of the node in the node-set ordered in document order
  >   if the axis is a forward axis and ordered in reverse
  >   document order if the axis is a reverse axis. [...]
  >   For each node in the node-set to be filtered,
  >   the PredicateExpr is evaluated [...]
  >   with the proximity position of the node
  >   in the node-set with respect to the axis
  >   as the context position [...]
  >
  > XSL Transformations (XSLT) Version 1.0
  >
  >   11.2 Values of Variables and Parameters
  >
  >   [...] If the variable-binding element has a select
  >   attribute, then the value of the attribute must be
  >   an expression and the value of the variable is the object
  >   that results from evaluating the expression. [...]

If this is all what we have then the result of the above test
should be "1", since the value of a variable is an object
rather than an expression and thus is an (unordered) node-set.
Therefore, its members, when forced to be ordered,
should be ordered in document order.
Is it a definite answer? Does it depend on a realization?

I have run into this question because the result of
MSXML 3.0 and Saxon differs from that of MSXML 4.0:
the former give "1", while the latter gives "2".
Who is right? Or they are both right?

Thanks.

-- 
Alexander E. Gutman

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