WMS output formats

[Alexandre Fellay]

I don't understand some aspects of the behavior of Mapserver (version 4.4.2) as 
WMS server. My problem is as follows :
I want to publish one single raster layer, and only in jpeg format (all other 
formats being unsuitable for various reasons). So I put in my mapfile

IMAGETYPE jpeg

I add an OUTPUFORMAT object :

OUTPUTFORMAT
   NAME jpeg
   DRIVER "GD/JPEG"
   MIMETYPE "image/jpeg"
   IMAGEMODE RGB
   FORMATOPTION QUALITY=88
   EXTENSION "jpg"
END

and the required METADATA in my layer :
   METADATA
     "wms_title" "blabla"
     "wms_srs"   "EPSG:21781 EPSG:4326 EPSG:32632"
     "wms_server_version" "1.1.1"
     "wms_format" "image/jpeg"
     "wms_name" "blabla"
   END

The surprise is in the GetCapabilities answer: other formats are advertised as well
       <Format>image/jpeg</Format>
       <Format>image/gif</Format>
       <Format>image/png</Format>
       <Format>image/png; mode=24bit</Format>
       <Format>image/wbmp</Format>
       <Format>image/tiff</Format>

And, to make things worse, some wms clients (Gaia 2 for example) seem to have a 
png default format, resulting in an ugly 8bit image.

Is it possible to really limit the supported output formats list ?

Alexandre F