.. _cgi_introduction:

*****************************************************************************
 MapServer CGI Introduction
*****************************************************************************


Notes
=====

*  Variable names are not case sensitive.
*  In cases where multiple values are associated with a variable (eg. 
   mapext), the values must be seperated by spaces (or their escaped 
   equivalents for GET requests).
*  Variable contents are checked for appropriate data types and magnitude 
   as they are loaded.
*  Any CGI Variable not listed below is simply stored and can be 
   referenced within a template file. 

Changes
=======

From MapServer version 4.x to version 5.x
-----------------------------------------

*  Modifying map parameters through a URL has changed to allow for 
   chunks of a mapfile to be modified at once.  The syntax has changed
   accordingly, so please see the :ref:`cgi_mapfile_change_parameters`
   section.

From MapServer version 3.x to version 4.x
-----------------------------------------

*  New way to perform attribute queries: No longer do you set a layer 
   filter, but rather you pass a query string (and optionally a query 
   item) to the query function. To do this two new CGI parameters were 
   added to MapServer: `QSTRING` and `QITEM`.
*  `SAVEMAP` is switched off: The SAVEMAP functionality is considered 
   insecure, since the saved files are accessible by everyone.
*  `TEMPLATE` has been removed, since the map_web_template syntax can be 
   used to alter a template file. Simplifies security maintenance by only 
   having to deal with this option in a single place. Note that the 
   `TEMPLATEPATTERN` of the mapfile has to be used to enable this feature.