[OpenLayers-Users] How to add an overlay to the map, but not select it by default

[Adrian Popa]

Hello everyone,

I'm trying to add several overlay layers (from mapserver) to an 
openlayers map. Everything works as expected, but when the map loads, 
all the overlay layers are selected. I would like to have the ability 
(programmatically) to select which layers are selected by default. 
Here's an example of how I enable an overlay layer:

var rtc = new OpenLayers.Layer.MapServer("Test", 
"http://terra/cgi-bin/mapserv", { map='/var/www/html/map/rtc.map', 
transparent:true, format:'png',
map_imagetype: 'agg',layers: 'mylayer', maxExtent: new 
OpenLayers.Bounds(20.26, 43.16, 29.70, 48.46), maxResolution: 
156543,units: 'm'},
{ isBaseLayer:false, projection: sphericalMercator, singleTile: 'true'});

map.addLayers([rtc]);

I was unable to find a method in the documentation to allow me to 
'deselect' specific layers. If there is, I would appreciate a pointer.

Thanks in advance,
Adrian