Passing Parameters to Mapserver

I was bitten 4 hours searching for this in the mailing list. I have a postgis layer defined in mapserver map file as follows:

LAYER
        NAME "pois"
        STATUS DEFAULT
		GROUP "pois"
        TYPE POINT
 
		CONNECTIONTYPE postgis
		PROCESSING "CLOSE_CONNECTION=DEFER"
		CONNECTION "user=lbs password=xtlme15n dbname=beijing_stat host=192.168.1.211 port=5432"
		#DATA "the_geom from (SELECT poi_id, the_geom FROM poi WHERE new_block_id = 7) as foo USING UNIQUE poi_id USING SRID=4326"
		DATA "the_geom from poi as foo USING UNIQUE poi_id USING SRID=4326"
 
		FILTER "new_block_id=%myid%"
 
		CLASS
			NAME "block-pois"
    		        STYLE
				SYMBOL "circle"
     			        COLOR 255 0 0
				SIZE 10
   			END
  		END
END

Traditionally, I could append and change the FILTER attribute by passing it to the Mapserver CGI as follows:
map.pois.filter=new_block_id%3D700.

Apparently, this changed with Mapserver 5.0. Please see MapServer 4.10 to 5.0 Migration Guide. Thanks to this mailing list thread, it turned out that we need to pass a value to a custom variable set in the mapfile for security reasons. Hope this one, goes in to the docs. I was hoping to comment out in the Mapserver Documentation but registration is holding me off with a ‘Connection Refused’.