p:input in viewport

In 2.2 Inputs and Outputs we say:

"Each component declares its input and output ports. [Definition: The input
ports declared on a component are its *declared inputs*.] [Definition: The
output ports declared on a component are its *declared outputs*.]"

In 4.2.8 we say:

  "The p:viewport component has exactly one input named "source" and exactly
one output named "result"."

In 4.1.2 Associating Documents with Ports we say:

"When a pipe is used to bind an input, the specified port must be in the *
outputs* of the current context. When a pipe is used to bind an output, the
specified port must be in the *inputs* of the context."

As such, that means we've got the binding of "source" in the viewport's
context's inputs and "result" in the
viewport's context's outputs.  That means it isn't available according to
4.1.2 in the outputs of the current context
and can't be bound to by a contained step.

As an aside, 4.2.8  should say that "current" is added to the outputs of the
current context--which
it doesn't and that seems like a simple bug in the spec.


-- 
--Alex Milowski
"The excellence of grammar as a guide is proportional to the paucity of the
inflexions, i.e. to the degree of analysis effected by the language
considered."

Bertrand Russell in a footnote of Principles of Mathematics