"RS" in communication standards RS232 and RS485 stands for "Recommended Standard". But what information does "232" or "422" or "485" convey in the name? What naming convention is used for numbers succeeding the letters "RS" when naming the RS standards?

locked by Dave Tweed Feb 2 '17 at 21:46

This post has been locked due to the high amount of off-topic comments generated. For extended discussions, please use chat.

up vote 27 down vote accepted

It's the document serial number of the standard. Same reason why the HTTP protocol is also known as RFC2616 and the Javascript programming language is also known as ECMA262.

The numbers themselves have no meaning. For example while EIA232 specifies the electrical characteristics of a digital serial communications system, EIA222 specifies standards for antenna masts and RS225 is a standard for RF connectors.

Wikipedia has an incomplete list of popular RS/EIA standards: https://en.wikipedia.org/wiki/EIA_standards

  • 3
    RFC numbers do occasionally have a little structure, but as far as I know it's limited to things like reusing the last two or three digits of the number for an update to an important standard (e.g. RFC 822, the original core email specification, was superseded by RFC 2822 and then RFC 5322). – zwol Feb 1 '17 at 16:29
  • 3
    I don't know anyone who refers to the HTTP protocol as RFC2616 -- the document itself gives the protocol a name, so that is its name. (It's not even specified by RFC 2616 any more -- it was replaced by RFCs 7230 through 7237 in 2014). – Henning Makholm Feb 1 '17 at 18:50
  • 3
    @HenningMakholm -- it's probably exactly because the IETF doesn't maintain document numbers for a specific topic that we don't use the document number in the name of protocols. Other standards bodies typically use a versioning scheme (e.g. appending a date after the document number as in Crowley's example of ISO9001:2016 referring to a specific version of ISO9001) that allows the base number to remain the same when new versions of a standard are released. That makes it much more convenient to use the document number to refer to the standard. – Periata Breatta Feb 2 '17 at 11:17
  • @Periata Breatta Thank You.Reasonable explanation. – Sonam Khullar Feb 2 '17 at 13:03

It signifies nothing; it's part of a sequential list of EIA standards: -

enter image description here

  • Well, it refers to one very specific item in that list. Isn't that significant? – Octopus Feb 2 '17 at 3:10
  • @Octopus maybe you can be a little clearer about what you mean? – Andy aka Feb 2 '17 at 8:14
  • You said "it signifies nothing". It signifies which paragraph or section it is covered under. – Octopus Feb 3 '17 at 16:52
  • @Octopus maybe, if you became more pedantic in your attitude towards formally accepting answers to some of the questions you've raised, I'd be somewhat impressed by your cutting humour. – Andy aka Feb 3 '17 at 16:59
  • I only called you out on that statement because you're implying that the OP asked an invalid question. "What does this signify?", "Nothing!" It's actually an excellent question. You're not impressing anybody. If your job here is to invalidate questions and comments then well done. – Octopus Feb 3 '17 at 17:07

RS = recommended standard

RFC = request for comment,

numbers don't have any real meaning

  • 1
    The OP knows about RS already, and doesn’t mention RFC. – JDługosz Feb 2 '17 at 8:08
  • 1
    Historically, RS = Radio Sector. This was the sub-department of the EIA that was involved in the standard. It was adapted to Recommended Standard over time. – Rev1.0 Feb 13 '17 at 13:15

Not the answer you're looking for? Browse other questions tagged or ask your own question.