# fn:parse-ietf-date - XPath XQuery Reference

Parses a string containing the date and time in IETF format, returning the corresponding
               xs:dateTime value.deterministiccontext-independentfocus-independentThe function accepts a string matching the production input in the
            following grammar:input::=S? (dayname ","? S)? ((datespec S time) | asctime) S?dayname::="Mon" | "Tue" | "Wed" | "Thu" | "Fri" | "Sat" | "Sun" | "Monday | "Tuesday"
                     | "Wednesday" | "Thursday" | "Friday" | "Saturday" | "Sunday"datespec::=daynum dsep monthname dsep yearasctime::=monthname dsep daynum S time S yeardsep::=S | (S? "-" S?)daynum::=digit digit?year::=digit digit (digit digit)?digit::=[0-9]monthname::="Jan" | "Feb" | "Mar" | "Apr" | "May" | "Jun" | "Jul" | "Aug" | "Sep" |
                     "Oct" | "Nov" | "Dec"time::=hours ":" minutes (":" seconds)? (S? timezone)?hours::=digit digit?minutes::=digit digitseconds::=digit digit ("." digit+)?timezone::=tzname | tzoffset (S? "(" S? tzname S? ")")?tzname::="UT" | "UTC" | "GMT" | "EST" | "EDT" | "CST" | "CDT" | "MST" | "MDT" | "PST"
                     | "PDT" tzoffset::=("+"|"-") hours ":"? minutes?S::=( x09 | x0A | x0D | x20 )+The input is case-insensitive: upper-case and lower-case distinctions in the above
            grammar show the conventional usage, but otherwise have no significance.If the input is an empty sequence, the result is an empty sequence.The dayname, if present, is ignored.The daynum, monthname, and year supply the day,
            month, and year of the resulting xs:dateTime value. A two-digit year
               must have 1900 added to it. A year such as 0070 is to be treated
            as given; negative years are not permitted.The hours, minutes, and seconds (including
            fractional seconds) values supply the corresponding components of the resulting
               xs:dateTime value; if the seconds value 
            or the fractional seconds value is absent then zero
            is assumed.If both a tzoffset and a tzname are supplied then the
               tzname is ignored.If a tzoffset is supplied then this defines the hours and minutes parts of the timezone offset:If it contains a colon, this separates the hours part from the minutes part.Otherwise, the grammar allows a sequence of from one to four digits. These are interpreted
            as H, HH, HMM, or HHMM respectively, where H
            or HH is the hours part, and MM (if present) is the minutes part.If the minutes part is absent it defaults to 00.If a tzname is supplied with no tzoffset then it is translated
            to a timezone offset as follows:tznameOffsetUT, UTC, GMT00:00EST-05:00EDT-04:00CST-06:00CDT-05:00MST-07:00MDT-06:00PST-08:00PDT-07:00If neither a tzoffset nor tzname is supplied, a timezone
            offset of 00:00 is assumed.fn:parse-ietf-date("Wed, 06 Jun 1994 07:29:35 GMT")xs:dateTime("1994-06-06T07:29:35Z")fn:parse-ietf-date("Wed, 6 Jun 94 07:29:35 GMT")xs:dateTime("1994-06-06T07:29:35Z")fn:parse-ietf-date("Wed Jun 06 11:54:45 EST 2013")xs:dateTime("2013-06-06T11:54:45-05:00")fn:parse-ietf-date("Sunday, 06-Nov-94 08:49:37 GMT")xs:dateTime("1994-11-06T08:49:37Z")fn:parse-ietf-date("Wed, 6 Jun 94 07:29:35 +0500")xs:dateTime("1994-06-06T07:29:35+05:00")A dynamic error is raised  if the input does
            not match the grammar, or if the resulting date/time value is invalid (for example, 31
            February).The parse-ietf-date function attempts to interpret its input as a date
            in any of the three formats specified by HTTP .These formats are used widely on the Internet to represent timestamps, and were
            specified in: (electronic mail), extended in  to allow four-digit years; (Usenet Messages), obsoleted by ;POSIX asctime() format (HTTP) officially uses a subset of those three formats restricted to GMT.The grammar for this function is slightly more liberal than the RFCs (reflecting the internet tradition of being liberal in what is accepted).
            For example the function:Accepts a single-digit value where appropriate in place of a two-digit value with a leading zero (so
                  "Wed 1 Jun" is acceptable in place of "Wed 01 Jun", and the timezone offset "-5:00" is equivalent
                  to "-05:00")Accepts one or more whitespace characters (x20, x09, x0A, x0D) wherever a single
                  space is required, and allows whitespace to be omitted where it is not required
                  for parsingAccepts and ignores whitespace characters (x20, x09, x0A, x0D) at the start or end
                  of the string.In new protocols IETF recommends the format of  which is based on a profile of
            ISO 8601 similar to that already used in XPath and XSD, but the "approximate" 
            format described here is very widely used.An  date can be generated approximately using fn:format-dateTime with a picture
            string of "[FNn3], [D01] [MNn3] [Y04] [H01]:[m01]:[s01] [Z0000]".