Introductory pipeline prose

Here goes:

Few specifications are implemented in their entirety, in exactly the
same way, by every implementor. Many specifications contain optional
features or areas of acknowledged variation and some implementors
choose to ignore required features that aren't needed by the community
they serve, chosing to trade conformance for other benefits.

In the case of XML, there are exists not only optionality in the XML
Recommendation itself, but there are a whole family of additional
specifications which an implementor may choose to support or ignore.
In principle, there are an enormous number of possible variations. In
practice, there are dependencies between the specifications that limit
the number of possible variations and implementors aren't motivated to
implement completely arbitrary selections.

Just as the Infoset gave the community a vocabulary for discussing the
items produced by a parser, describing profiles, specific sets of
features drawn from the family of specifications, and providing names
for them, is an attempt to give the community a vocabulary for
describing common sets of higher level features.

One goal of this work is to help establish a lower bound on the number
and nature of features supported. Establishing that we can communicate
by sending XML documents back and forth is predicated on the notion
that we have the same understanding of those documents. While we might
wish for the richest possible understanding, that's not likely to be
supported by the widest range of implementations. Establishing a few
basic profiles, we hope, provides a foundation on which other
specifications can build.

                                        Be seeing you,
                                          norm

-- 
Norman Walsh
Lead Engineer
MarkLogic Corporation
Phone: +1 413 624 6676
www.marklogic.com