Namespace confusion

This page is for collecting evidence about Namespaces in XML not being helpful.

Bugs caused by Namespaces

• Redeclaring a namespace breaks
• Prefix difference breaks
• Prefix difference breaks
• Wrong prefix used causing bad expansion
• Feed aggregators failing with prefixed XHTML elements
• Declared prefix and used prefix differ
• RDFa used without declaring prefix
• Hard-wired prefix

Wrong documentation about Namespaces

• Wrong URI declared (slash missing)
• Prefix missing

Namespace-related questions

• prefix difference
• declaring the same nsprefix twice on one element

Namespace-related anecdotes

• “90% of the technical questions” writes the O’Reilly XForms book author
• “Experience shows XML namespaces can be a common cause of confusion”
• “If there is any one of the W3C's family of XML specifications, that has caused me the most grief, XML Namespaces is probably it.” writes the Lead Developer of MSXML and System.Xml
• “I have a picture that made the audience at the session gasp in disbelief.” (Picture showing lots of namespace declarations.)

Related pages on other wikis

• Namespaces considered harmful on the Microformats wiki

E-mails detailing lists of problems with namespaces

• A WHATWG e-mail by Henri Sivonen in the context of RDFa

E-mails showing confusion with namespaces

• Karl Dubost on xml:lang in text/html (Admittedly this is a rather hard case given that {lang}, {xml:lang}, and xml{lang} all exist.)
• Confusion about what
  declares (Initially suspected to be sarcasm!)