RFC 6455, "The WebSocket Protocol", December 2011

Note: This RFC has been updated by RFC 7936, RFC 8307, RFC 8441

Errata ID: 3912
Status: Rejected
Type: Technical
Publication Format(s) : TEXT
Reported By: Mattias Ekendahl
Date Reported: 2014-03-05
Rejected by: Barry Leiba
Date Rejected: 2014-03-24

Section 5.2 says:

    frame-payload-length    = ( %x00-7D )
                            / ( %x7E frame-payload-length-16 )
                            / ( %x7F frame-payload-length-63 )
                            ; 7, 7+16, or 7+64 bits in length,
                            ; respectively

    frame-payload-length-16 = %x0000-FFFF ; 16 bits in length

    frame-payload-length-63 = %x0000000000000000-7FFFFFFFFFFFFFFF
                            ; 64 bits in length

It should say:

    frame-payload-length    = ( %x00-7D )
                            / ( %x7E frame-payload-length-16 )
                            / ( %x7F frame-payload-length-64 )
                            ; 7, 7+16, or 7+64 bits in length,
                            ; respectively

    frame-payload-length-16 = %x0000-FFFF ; 16 bits in length

    frame-payload-length-64 = %x0000000000000000-FFFFFFFFFFFFFFFF
                            ; 64 bits in length

Notes:

Name of field and range is implying that it should be 63 bits in length, but documentation is saying 64 bits in 2 places.
--VERIFIER NOTES--
The intended interpretation is that lexically the field is 64 bit long but the value space is constrained to 63 bit (so the length can be represented in a 64 signed integer, with the sign bit always zero). It is a bit unconventional to use ABNF like this, but it is explained in Section 5.2.

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