All of my shapefiles have exactly the same .prj files with this content:

    PROJCS["GRS_1980_Transverse_Mercator",
    GEOGCS["GCS_GRS_1980",
    DATUM["D_GRS_1980",
    SPHEROID["GRS_1980",6378137,298.257222101]],
    PRIMEM["Greenwich",0],
    UNIT["Degree",0.017453292519943295]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["False_Easting",500000],
    PARAMETER["False_Northing",-6000000],
    PARAMETER["Central_Meridian",24],
    PARAMETER["Scale_Factor",0.9996],
    PARAMETER["Latitude_Of_Origin",0],
    UNIT["Meter",1]]

I want to know what changes I must make to these two lines in my mapfile, for it to fit my shapefiles:

    "wms_srs"             "EPSG:4269 EPSG:4326"
    "init=epsg:42304"

my **mapfile2.map** looks like this:

    MAP
        # mapfile prieks MapServer + Openlayers testa aplikacijas
    
        CONFIG "MS_ERRORFILE" "C:/MS4W/ms4w/apps/gis/tmp/ms_error.txt"
        DEBUG 5
        NAME latvijas_karte
        STATUS ON
        SIZE 800 500
    
        EXTENT 313187.4 146161.56 766469.92 470367.64
        
        UNITS METERS
        SHAPEPATH "shapefiles"
        IMAGECOLOR 155 155 155
       
        WEB
            TEMPLATE "template.html"
            IMAGEPATH "C:/MS4W/ms4w/Apache/htdocs/output/"
            IMAGEURL "/output/"
            
            METADATA
                "wms_title"           "MapServer Openlayers demo application"
                "wms_onlineresource"  "http://localhost:1025/cgi-bin/mapserv?map=C:\MS4W\ms4w\apps\gis\mapfile2.map&"
                "wms_srs"             "EPSG:4269 EPSG:4326"
                # "wms_enable_request"
            END
        END
    
        PROJECTION
            "init=epsg:42304"
        END
        
    # example layer
        LAYER
            METADATA
                "wms_title"           "example layer"
                "wms_srs"             "EPSG:4269 EPSG:4326"
            END
            PROJECTION
                "init=epsg:42304"
            END
            NAME "lat_rob_region"
            DATA lat_rob_region
            STATUS DEFAULT
            TYPE POLYGON
            CLASS
                NAME "fons"
                STYLE
                    COLOR 0 255 0
                END
            END
        END
    END


----------

**Edit #1:**

I tried using EPSG:3059 (LKS92 / Latvia TM), since the maps are Latvian.
Accessing `http://localhost:1025/cgi-bin/mapserv.exe?map=C:\MS4W\ms4w\apps\gis\mapfile2.map&SERVICE=WMS&VERSION=1.1.1%20&REQUEST=GetCapabilities` gave me an XML document which describes the WMS, no error messages.

Now when I try to test my WMS via this link: `http://localhost:1025/cgi-bin/mapserv.exe?map=C:\MS4W\ms4w\apps\gis\mapfile2.map&SERVICE=WMS&VERSION=1.1.1%20&REQUEST=GetMap&LAYERS=lat_rob_region&STYLES=&SRS=EPSG:3059%20&BBOX=313187.4,146161.56,766469.92,470367.64&WIDTH=800&HEIGHT=600%20&FORMAT=image/png`

I get this error message:

    msWMSLoadGetMapParams(): WMS server error. Invalid SRS given : SRS must be valid for all requested layers. I can't figure out what epsg code to use.

  [1]: http://mapserver.org/ogc/wms_server.html
  [2]: http://mapserver.org/errors.html#msprocessprojection-no-options-found-in-init-file
  [3]: http://gis.stackexchange.com/questions/7839/best-practices-for-identifying-the-unknown-coordinate-system-of-a-shapefile
  [4]: http://mapserver.org/ogc/wms_server.html