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I've often seen "bis" appended to versions of protocols (eg v.34bis or httpbis).

What does "bis" mean or stand for?

A telecom engineer I know thinks it might be French in origin.

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Is the question about the general meaning of "bis" or more specific to how HTTPbis relates to HTTP? –  Bruno Feb 2 '12 at 0:54
@Bruno - it was specifically about what bis means in general, but I'd definitely be interested in http vs httpbis –  J. Polfer Feb 2 '12 at 0:56
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up vote 17 down vote accepted

As others have already said, "bis" comes from "twice" or "repeat". It's used to indicate a second variant of something (although usually with only minor variations that don't warrant a new name).

In the context of HTTP, HTTPbis is the name of the working group in charge of refining HTTP. According to its charter:


The working group will refine RFC2616 to:

  • Incorporate errata and updates (e.g., references, IANA registries, ABNF)
  • Fix editorial problems which have led to misunderstandings of the specification
  • Clarify conformance requirements
  • Remove known ambiguities where they affect interoperability
  • Clarify existing methods of extensibility
  • Remove or deprecate those features that are not widely implemented and also unduly affect interoperability
  • Where necessary, add implementation advice



In doing so, it should consider:

  • Implementer experience
  • Demonstrated use of HTTP
  • Impact on existing implementations and deployments


The last paragraph (emphasis mine) explains why they've used "bis" in this context, since they explicitly don't want a new version.

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(from http://whatis.techtarget.com/definition/0,,sid9_gci211669,00.html)

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