$.fn.validate_field = function(options){
	settings = jQuery.extend({
		req : "required",
		val_type : "alpha_num", 
    	msg_div : "error_msg",
    	val_page : root_path + "errchk_common.php",
    	graphic : true,
    	valid_img : root_path + "images/forms/valid_plus.gif",
    	invalid_img : root_path + "images/forms/valid_minus.gif"
    	
  	},options);
	
	var fid = $(this).attr("id");
	var fname = $(this).attr("name");
	var fvalue = $(this).val();
	var val_str = "fname=" + fname + "&fvalue=" + fvalue + "&req=" + settings.req + "&val_type=" + settings.val_type;

	$.ajax({
    	type: "POST",
    	url: settings.val_page,
    	data: val_str,
    	dataType: "json",
    	success: function(data){
    		
    		var qno = data['fname'];
    		var valid = data['valid'];

    		if(valid == "yes"){
    		
    			$("#" + fid + "_check").val('true');
    			if(settings.graphic){
    				$("#" + fid + "_img").attr({src : settings.valid_img, alt : "plus" });
    			}
    			
    		} else {
    		
    			$("#" + fid + "_check").val('false');
    			if(settings.graphic){
    				$("#" + fid + "_img").attr({src : settings.invalid_img, alt : "minus" });
    			}
    			
    		}
 	
    	},
    	error: function(XMLHttpRequest, textStatus, errorThrown){
    		alert("THERE HAS BEEN AN ERROR: " + textStatus + " - " + errorThrown);
    	}
    });

}