What expression or query will yield a variable reference?

[Tim Hallwyl <tim@hallwyl.dk>]

Dear Sirs,

I have a few questions regarding evaluation of queries and expressions, 
that I hope to discuss with you. I noticed that this list has not been 
used for quite a while, so if you know of an other forum I should use 
please let me know.


In the specification, section 8.2.1 "Enclosing Elements", it says:

Evaluation of a WS-BPEL expression or query will yield one of the 
following  ...:
- a single XML infoset item ...
- a collection of XML infoset items ...
- a sequence of CIIs for simple type data ...
- a variable reference: e.g. <from>$myFooVar</from>

I do not understand the variable reference -- why would the expression 
"$myFooVar" not result in either single XML infoset item or sequence of 
CIIs?

What exactly is meant by "variable reference"? I tried to categorize the 
types of queries and expressions, but I cannot see which kind of 
expressions that should yield a variable reference.

The example <from>$myFooVar</from> must be a General Expression as 
listed in section 8.3 "Expressions".

In section 8.3.5 "General Expressions", is says that general expressions 
"results in any XPath value type (string, number, or Boolean)."

However, in section 8.4 "Assignment" under "Expression variant" is says:

This computed value of the expression MUST be one of the followings:
- a single XML information item other than a CII ...
- a sequence of zero or more CIIs ...

To summarize what confuses me is...
8.2.1: <from>$myFooVar</from> returns a variable reference,
8.3  : expressions in assignment are General Expressions,
8.3.5: General Expressions results in string, number, or Boolean,
8.4  : result is a single XML information item or a sequence of CIIs

I am looking forward to hearing your opinion. Thanks.

-- 
Regards


Tim Hallwyl
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