IANA Considerations for Three Letter Acronyms
RFC - Informational
(April 2009; Errata)
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RFC 5513 (Informational)
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Network Working Group A. Farrel
Request for Comments: 5513 Old Dog Consulting
Category: Informational 1 April 2009
IANA Considerations for Three Letter Acronyms
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Three Letter Acronyms (TLAs) are commonly used to identify components
of networks or protocols as designed or specified within the IETF. A
common concern is that one acronym may have multiple expansions.
While this may not have been an issue in the past, network
convergence means that protocols that did not previously operate
together are now found in close proximity. This results in
contention for acronyms, and confusion in interpretation. Such
confusion has the potential to degrade the performance of the
Internet as misunderstandings lead to misconfiguration or other
Farrel Informational [Page 1]
RFC 5513 TLAs April 2009
Given the growing use of TLAs and the relatively small number
available, this document specifies a Badly Construed Proposal (BCP)
for the management of a registry of TLAs within the IETF, and the
procedures for the allocation of new TLAs from the registry.
A Three-Letter Acronym (TLA) is a popular form of abbreviation
usually based on the initial letters of a three-word term. A formal
definition of a TLA is provided in Section 2.
TLAs are particularly popular within the Internet community where
they serve as abbreviations in the spoken and written word. As their
popularity has grown, the measure of the value of an RFC (q.v.) is
not only its successful implementation, interoperability, and
deployment, but also the number of TLAs included in the text.
For example, the Transmission Control Protocol (itself a TLA - TCP)
[RFC0793] is extremely successful. The specification contains no
fewer than 20 distinct TLAs (although it should be noted that some
are simple abbreviations rather than proper acronyms). On the other
hand, the Internet Stream Protocol Version 2 [RFC1819] is ambiguously
referred to using the TLA ST2, and also as STII which is clearly not
a TLA. Further, the STII specification contains only 12 distinct
TLAs, and it should be no surprise that STII has been far less
successful than TCP.
A common concern amongst diligent protocol implementers is that one
acronym may have multiple expansions. While this may not have been
an issue in the past, network convergence means that protocols that
did not previously operate together are now found in close proximity.
Not only does this result in contention for acronyms, and confusion
in interpretation of specification, it also leads to many wasted
hours trying to select appropriate and suitably-unique names for
variables within source code implementations. Such confusion has the
potential to degrade the performance of the Internet as
misunderstandings lead to coding errors, compilation failures,
misconfiguration, and other operating errors.
Furthermore, it should be noted that we are rapidly approaching World
Acronym Depletion (WAD). It has been estimated that, at the current
rate of TLA allocation, we will run out by the end of September this
year. This timescale could be worsened if there is the expected
growth in demand for mobile acronyms, IP-TLAs, and TLA-on-demand.
According to the definition provided in Section 2, there are 36**3 -
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