Re: [apps-discuss] Review of: draft-yevstifeyev-abnf-separated-lists-02

["Thomson, Martin" <[e-mail]>]

On 2010-12-13 at 20:56:08, Julian Reschke wrote:
> "Wherever this construct is used, null elements are allowed, but do not
> contribute to the count of elements present. That is, "(element), ,
> (element) " is permitted, but counts as only two elements. Therefore,
> where at least one element is required, at least one non-null element
> MUST be present. Default values are 0 and infinity so that "#element"
> allows any number, including zero; "1#element" requires at least one;
> and "1#2element" allows one or two." --
> <http://greenbytes.de/tech/webdav/rfc2616.html#rfc.section.2.1>

For HTTP, the # rule can be handled with some tweaking...

  a = #b

->

  a = *LWS *^(*LWS "," *LWS)[b]

It means that this isn't as directly usable by HTTP, though establishing a convention would make this a little easier.

  a = *LWS *^COMMA[b]