usefor-article-09 February 2003

6.18.  User-Agent

   The User-Agent-header contains information about the user agent
   (typically a newsreader) generating the article, for statistical
   purposes and tracing of standards violations to specific software
   needing correction. Although not one of the mandatory headers,
   posting agents SHOULD normally include it. It is also intended that
   this header be suitable for use in Email.

      header              =/ User-Agent-header
      User-Agent-header   = "User-Agent" ":" SP User-Agent-content
                     *( ";" extension-parameter )
      User-Agent-content  = product *( CFWS product )
      product             = [CFWS] token [CFWS] [ "/" product-version ]
      product-version     = [CFWS] token [CFWS]

   This header MAY contain multiple product-tokens identifying the agent
   and any subproducts which form a significant part of the posting
   agent, listed in order of their significance for identifying the
   application. Product-tokens should be short and to the point - they
   MUST NOT be used for information beyond the canonical name of the
   product and its version.  Injecting agents MAY include product
   information for themselves (such as "INN/1.7.2"), but relaying and
   serving agents MUST NOT generate or modify this header to list
   themselves.

        NOTE: A product, being composed of a token, can contain only
        US-ASCII characters. Where the full name of an agent is
        expressed in a language requiring non-ASCII characters, it is
        suggested that an arbitrary (but easily recognizable) US_ASCII
        token be provided, followed by the full name in the form of a
        comment.

        NOTE: Minor variations from [RFC 2616] which describes a similar
        facility for the HTTP protocol:

        1.    "{" and "}" are allowed in a token (product and product-
    version) in Netnews,

        2.    Comments are permitted wherever whitespace is allowed.

        NOTE: Comments should be restricted to information regarding the
        product named to their left, such as its full name or platform
        information, and should be concise. Use as an advertising medium
        (in the mundane sense) is discouraged.

--- ../usefor-article-08/User-Agent.out          August 2002
+++ ../usefor-article-09/User-Agent.out          February 2003
@@ -4,14 +4,15 @@
    (typically a newsreader) generating the article, for statistical
    purposes and tracing of standards violations to specific software
    needing correction. Although not one of the mandatory headers,
-   posting agents SHOULD normally include it.
+   posting agents SHOULD normally include it. It is also intended that
+   this header be suitable for use in Email.
 
       header              =/ User-Agent-header
       User-Agent-header   = "User-Agent" ":" SP User-Agent-content
-                     *( ";" other-parameter )
-      User-Agent-content  = product-token *( CFWS product-token )
-      product-token       = value [ "/" product-version ]  ; see 4.1
-      product-version     = value
+                     *( ";" extension-parameter )
+      User-Agent-content  = product *( CFWS product )
+      product             = [CFWS] token [CFWS] [ "/" product-version ]
+      product-version     = [CFWS] token [CFWS]
 
    This header MAY contain multiple product-tokens identifying the agent
    and any subproducts which form a significant part of the posting
@@ -23,20 +24,23 @@
    serving agents MUST NOT generate or modify this header to list
    themselves.
 
-        NOTE: Variations from [RFC 2616] which describes a similar
-        facility for the HTTP protocol:
+        NOTE: A product, being composed of a token, can contain only
+        US-ASCII characters. Where the full name of an agent is
+        expressed in a language requiring non-ASCII characters, it is
+        suggested that an arbitrary (but easily recognizable) US_ASCII
+        token be provided, followed by the full name in the form of a
+        comment.
 
-        1.    use of arbitrary text or octets from character sets other
-    than US-ASCII in a product-token may require the use of a
-    quoted-string,
+        NOTE: Minor variations from [RFC 2616] which describes a similar
+        facility for the HTTP protocol:
 
-        2.    "{" and "}" are allowed in a value (product-token and
-    product-version) in Netnews,
+        1.    "{" and "}" are allowed in a token (product and product-
+    version) in Netnews,
 
-        3.    UTF-8 replaces ISO-8859-1 as charset assumption.
+        2.    Comments are permitted wherever whitespace is allowed.
 
         NOTE: Comments should be restricted to information regarding the
-        product named to their left such as platform information and
-        should be concise. Use as an advertising medium (in the mundane
-        sense) is discouraged.
+        product named to their left, such as its full name or platform
+        information, and should be concise. Use as an advertising medium
+        (in the mundane sense) is discouraged.