RE: Help: use-when and p:episode

I now actually think that in its present form, use-when is
underspecified. A the moment, the spec says that use-when "must contain
an XPath expression that can be evaluated statically". But what does
that really mean? How does that affect XPath extension functions like
p:step-available(), p:value-available() etc.?

For instance, does p:step-available() in use-when see only standard
XProc steps, or also other nested or imported steps? What about cases
like this:

<p:declare-step type="ex:step1"
                use-when="p:step-available('ex:step2')">
  ...
</p:declare-step>

<p:declare-step type="ex:step2"
                use-when="p:step-available('ex:step1')">
  ...
</p:declare-step>

Personally, I think we will have to be more specific about what you can
do in use-when, and what limitations are there if you use the XPath
extension functions in use-when expressions.

Regards,
Vojtech