Re: Include data that may be objectively generated someday?
It is generally and almost always a bad idea to include a named item without a provable rule for asserting its value. For interchange, this is worse for reasons Michael Kay mentions. There is a parallel circumstance in legal circles with an admonition not to pass 'forward-looking or preemptive laws' to address a situation which may but has not yet occurred. I forget the terminology but it came up in a question to Supreme Justice Kagan in her Senate hearings. In XML schema design, it is a bad idea to stake territory with pre-emptive element declarations "just in case". This creates a situation for competing camps to logjam standards and bad citations leading to inter alia confusion. Don't make law you can't enforce. Don't create requirements you cannot prove are necessary to the consuming process. len Quoting "Costello, Roger L." <firstname.lastname@example.org>: > Hi Folks, > > Is it good or bad to include, in an XML document, data that is > currently not objectively generated but may be in the future? > > Please allow me to explain. > > Example: Below is information about a book. Suppose that today's > applications effectively process its markup and data: > > <Book> > <Title>_________</Title> > <Author>_________</Author> > <Date>_________</Date> > <ISBN>_________</ISBN> > <Publisher>_________</Publisher> > </Book> > > Now, consider the problem of determining how "enlightening" a book > is. Assume that there are no objective rules for determining the > enlightenment-capability of a book. Manual determination of the > enlightenment-capability of a book is subjective and yields mixed > results. Thus, automating the determination of the > enlightenment-capability of a book is problematic. > > Nonetheless, the developers of the Book XML vocabulary decide that > someday it may be possible to objectively measure the > enlightenment-capability of a book and applications will make > decisions based on enlightenment-capability data. So they decide > (today) to require that each book contain an > <Enlightenment-Capability> element: > > <Book> > <Enlightenment-Capability>__________</Enlightenment-Capability> > <Title>_________</Title> > <Author>_________</Author> > <Date>_________</Date> > <ISBN>_________</ISBN> > <Publisher>_________</Publisher> > </Book> > > Since the XML documents contain enlightenment-capability data > application developers figure "Hey, let's use it." So, suppose > applications (today) start making decisions based on the data in the > <Enlightenment-Capability> element. What will be the consequence? > > More generally, what will be the consequence of adding this element > to the Book XML vocabulary? > > /Roger > > _______________________________________________________________________ > > XML-DEV is a publicly archived, unmoderated list hosted by OASIS > to support XML implementation and development. To minimize > spam in the archives, you must subscribe before posting. > > [Un]Subscribe/change address: http://www.oasis-open.org/mlmanage/ > Or unsubscribe: email@example.com > subscribe: firstname.lastname@example.org > List archive: http://lists.xml.org/archives/xml-dev/ > List Guidelines: http://www.oasis-open.org/maillists/guidelines.php > > >
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