Re: [abnf-discuss] ABNF colloquialism for end-of-line

[Carsten Bormann <[e-mail]>]

Hi Dave,

On Nov 15, 2017, at 23:37, Dave Crocker <[e-mail]> wrote:
> 
> Given that the thread in CBOR says 'matching rules', I'm guessing that the goal here is to describe freeform data coming from the net.  Hence, requiring a simple, canonicalized data form is not appropriate.  (This is an essential point; if it's not correct, then what follows won't be either.)

The thread title unfortunately is misleading.

The ABNF is not for on-the wire packets, but for defining the syntax of the CDDL language (which then defines the syntax of the on-the-wire data items).

So this ABNF is about files on computers, which probably run a form of Linux/Unix or Windows (and very likely not pre-2001 classic MacOS).  So

   EOL = [CR] LF

is probably the right way to describe line ends for these files.

The context for this (with one exception) is

   NL = COMMENT / EOL
   COMMENT = ";" *(SP / VCHAR) EOL
   VCHAR = %x21-7E

Maybe NL is not the best name for the encompassing rule, but it is used only in one additional rule:

   WS = SP / NL

Grüße, Carsten


PS.: If ABNF had cuts, I’d write

   EOL = [CR ^] LF

to get better errors on stray CRs.  Maybe not so important these days.