Re-introduce "format" keyword, with some differences

* Get rid of the "color" and "style" format attributes.
* Specify the different instance types which can be validated by attributes.
* Specify that if an instance is not of a type which the format attribute can
  validate, the validation MUST succeed.
* "regex" is an ECMA 262 regular expression, remove "/perl5" since these
  dialects are not compatible (perl5 supports lookbehinds, ECMA 262 doesn't).
* Remove paragraph allowing other format attributes to be specified.

Author: fge

draft-04/schema

@@ -69,7 +69,8 @@
 		},
 
 		"pattern" : {
-			"type" : "string"
+			"type" : "string",
+			"format": "regex"
 		},
 
 		"items" : {
@@ -146,15 +147,18 @@
 		},
 
 		"id" : {
-			"type" : "string"
+			"type" : "string",
+			"format": "uri"
 		},
 
 		"$ref" : {
-			"type" : "string"
+			"type" : "string",
+			"format": "uri"
 		},
 
 		"$schema" : {
-			"type" : "string"
+			"type" : "string",
+			"format": "uri"
 		},
 
 		"title" : {

draft-zyp-json-schema-04.xml

@@ -463,7 +463,39 @@ Content-Type: application/json;
 					</list>
 				</t>
 			</section>
-			
+
+                        <section title="format">
+                               <t>This property helps to refine the type of data, content type, or microformat an instance value must adhere to. A format
+                               attribute MAY be one of the values listed below, and if so, SHOULD adhere to the semantics describing for the format. A format
+                               SHOULD only be used to give meaning to primitive types (string, integer, number, or boolean). Validators MUST validate that the
+                               instance values conform to a format.</t>
+
+                               <t>A format attribute only validates a defined set of primitive types. If the primitive type of the currently validated instance
+                               is not a member of this set, the instance MUST be considered valid for this keyword. All format attributes defined below are
+                               listed along with the primitive types they validate.</t>
+
+                               <t>The following formats are predefined:
+
+                                       <list style="hanging">
+                                               <t hangText="date-time"> (string) This SHOULD be a date in ISO 8601 format of YYYY-MM-DDThh:mm:ssZ in UTC time.
+                                               This is the recommended form of date/timestamp.</t>
+                                               <t hangText="date">(string) This SHOULD be a date in the format of YYYY-MM-DD. It is recommended that you use the
+                                               "date-time" format instead of "date" unless you need to transfer only the date part.</t>
+                                               <t hangText="time">(string) This SHOULD be a time in the format of hh:mm:ss. It is recommended that you use the
+                                               "date-time" format instead of "time" unless you need to transfer only the time part.</t>
+                                               <t hangText="utc-millisec">(number) This SHOULD be the difference, measured in milliseconds, between the
+                                               specified time and midnight, 00:00 of January 1, 1970 UTC.</t>
+                                               <t hangText="regex">(string) This SHOULD be an ECMA 262 (ie, JavaScript) regular expression.</t>
+                                               <t hangText="phone">(string) This SHOULD be a phone number (format MAY follow E.123).</t>
+                                               <t hangText="uri">(string) This value SHOULD be a URI.</t>
+                                               <t hangText="email">(string) This SHOULD be an email address.</t>
+                                               <t hangText="ip-address">(string) This SHOULD be an ip version 4 address.</t>
+                                               <t hangText="ipv6">(string) This SHOULD be an ip version 6 address.</t>
+                                               <t hangText="host-name">(string) This SHOULD be a host-name.</t>
+                                       </list>
+                               </t>
+                        </section>
+
 			<section title="pattern" anchor="pattern">
 				<t>When the instance value is a string, this provides a regular expression that a string instance MUST match in order to be valid. Regular expressions SHOULD follow the regular expression specification from ECMA 262/Perl 5</t>
 			</section>