On renewing expired links

                        On renewing expired links

Regarding the construction of a hypertext link employing data from the
following example of link information (which information is accessed
when using the Lynx browser by depressing the "=" key):

   Linkname: NLM Gateway Expanded Item
        URL: http://gateway.nlm.nih.gov/gw/Cmd?GMResults
    Charset: utf-8
     Server: Apache/1.3.27 (Unix) ApacheJServ/1.1.2
       Date: Tue, 21 Jan 2003 23:54:18 GMT
   Post Data:
GM2K_FORM=GMResults&enterKey=&BROWSER_STATE=GMResults&ORBagentPort=14610&Sessio
nID=03012115430310000462&HIDDEN_TIMESTAMP=1043193521897&LAST_HIDDEN_TIMESTAMP=1
043193517193&UserSearchText=boller+1989+clinicopathologic&Destination+Page+%3A+
Header=1&TARGET_DB_NAME_Header=Pick+A+Collection&Expand+Item+%3A+1.x=0&Expand+I
tem+%3A+1.y=0&Destination+Page+%3A+Footer=1&TARGET_DB_NAME_Footer=Pick+A+Collec
tion
   Post Content Type: application/x-www-form-urlencoded    

in the anchor tag the "Post Data" would be joined to the URL with an
ampersand "&" (i.e. URL "&" post data) as follows:

    http://gateway.nlm.nih.gov/gw/Cmd?GMResults "&" GM2K_FORM...

The gaps and quotation marks enclosing the ampersand (...Results "&" GM2K...) 
having been placed to demonstrate the ampersand position in this explanation,
should not appear in the joining of the post data to the URL, thus yielding
a URL joined to the post data as follows:

    http://gateway.nlm.nih.gov/gw/Cmd?GMResults&GM2K_FORM...

As the ellipses (...) indicate, the post data is of course much longer
than "GM2K_FORM", all of which is included in the URL - post data
combination.

Given that these links expire after approximately 24 hours, a link
composed of data in the above example would expire at approximately "Wed,
22 Jan 2003 23:54:18 GMT".

Presumably the "HIDDEN_TIMESTAMP" data in the post data determines the
perishability of the link.

Further information on link construction and other aspects of HTML code
can be found via the following two links:
Grex HTML Tutorials
Lynx 2.4-FM accessible excerpts from HTML Quick Reference

Acknowledgement:
I am grateful to Jan Wolter Ph.D. for technical advice on the inclusion of
post data in hypertext link construction. 
Dr. Wolter's web site: http://www.unixpapa.com/

This site is edited by 
rksjr@cyberspace.org, 
and is hosted by Grex at: http://www.cyberspace.org.