If UseDateLastModified is set to True, DateLastModified will return the last modification date of the file transmitted by the user. The date is displayed using the local time zone. For the UTC date of the file, see the DateLastModifiedUTC property.

The DateLastModified property only works if the client-upload software sends this information. Neither Netscape Navigator nor Microsoft Internet Explorer send the file's modification date. SoftArtisans XFile transmits this information by inserting the "X-Last-Modified" header in the Request, when XFile's [XFRequest].UseXLastModified property is set to True.

The file modification date is always sent in GMT format to account for time zone differences between the browser and server.

If you are using a different upload client, use the following header to send the Last Modified date:

X-Last-Modified: Fri Dec 04 10:29:02 GMT 1998

Which is defined as follows:

date-time = day date time 4DIGIT ; Dow Mmm dd hh:mm:ss zzz yyyy day = "Mon" /
            "Tue" / "Wed" / "Thu" / "Fri" / "Sat" / "Sun" date = month 2DIGIT ; month day month
            = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / "Jul" / "Aug" / "Sep" / "Oct"
            / "Nov" / "Dec" time = hour zone ; ANSI hour = 2DIGIT ":" 2DIGIT ":" 2DIGIT ; 00:00:00
            - 23:59:59 zone = "UT" / "GMT" ; Universal Time