Changeset 400 for draft-ietf-httpbis/latest/p1-messaging.xml
- Timestamp:
- 15/11/08 19:45:44 (12 years ago)
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draft-ietf-httpbis/latest/p1-messaging.xml
r398 r400 347 347 A construct "#" is defined, similar to "*", for defining lists of 348 348 elements. The full form is "<n>#<m>element" indicating at least 349 <n> and at most <m> elements, each separated by one or more commas 350 (",") and &OPTIONAL; linear white space (OWS). This makes the usual 351 form of lists very easy; a rule such as 352 <figure><artwork type="example"> 353 ( *<x:ref>OWS</x:ref> element *( *<x:ref>OWS</x:ref> "," *<x:ref>OWS</x:ref> element ))</artwork></figure> 349 <n> and at most <m> elements, each separated by a single comma 350 (",") and optional whitespace (OWS). 354 351 </t> 352 <figure><preamble> 353 Thus, 354 </preamble><artwork type="example"> 355 1#element => element *( OWS "," OWS element ) 356 </artwork></figure> 357 <figure><preamble> 358 and: 359 </preamble><artwork type="example"> 360 #element => [ 1#element ] 361 </artwork></figure> 362 <figure><preamble> 363 and for n >= 1 and m > 1: 364 </preamble><artwork type="example"> 365 <n>#<m>element => element <n-1>*<m-1>( OWS "," OWS element ) 366 </artwork></figure> 355 367 <t> 356 can be shown as 357 <figure><artwork type="example"> 358 1#element</artwork></figure> 368 For compatibility with legacy list rules, recipients &SHOULD; accept empty 369 list elements. In other words, consumers would follow the list productions: 359 370 </t> 360 <t> 361 Wherever this construct is used, null elements are allowed, but do 362 not contribute to the count of elements present. That is, 363 "(element), , (element) " is permitted, but counts as only two 364 elements. Therefore, where at least one element is required, at 365 least one non-null element &MUST; be present. Default values are 0 366 and infinity so that "#element" allows any number, including zero; 367 "1#element" requires at least one; and "1#2element" allows one or 368 two. 369 </t> 371 <figure><artwork type="example"> 372 #element => [ ( "," / element ) *( OWS "," [ OWS element ] ) ] 373 374 1#element => *( "," OWS ) element *( OWS "," [ OWS element ] ) 375 </artwork></figure> 370 376 <t> 371 377 <cref anchor="abnf.list"> … … 4082 4088 <section title="Changes from RFC 2616" anchor="changes.from.rfc.2616"> 4083 4089 <t> 4090 Empty list elements in list productions have been deprecated. 4091 (<xref target="notation.abnf"/>) 4092 </t> 4093 <t> 4084 4094 Rules about implicit linear white space between certain grammar productions 4085 4095 have been removed; now it's only allowed when specifically pointed out … … 4696 4706 </t> 4697 4707 <t> 4708 Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>): 4709 <list style="symbols"> 4710 <t> 4711 Rewrite definition of list rules, deprecate empty list elements. 4712 </t> 4713 </list> 4714 </t> 4715 <t> 4698 4716 Other changes: 4699 4717 <list style="symbols">
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