Example how to set up named styles in Mapserver

style_test.map

MAP
	# Style test mapfile, how to set up named styles in mapserver
	#
	# Lars Schylberg, 2020-09-15
	#
	# example: root layers access: LAYERS=ST&styles=color&
	#  individual layers: LAYERS=square,circle&styles=green,grey&
	#  default:    LAYERS=ST&styles=&
	#  or 		   LAYERS=ST&styles=default&
	# Gives correct GetCapabilities response
	#
    NAME ST
    EXTENT 0 0 20 15
    SIZE 200 150
    UNITS DD
    IMAGECOLOR 200 200 200
    CONFIG "MS_ERRORFILE" "/tmp/style_test.log"
    DEBUG 5

    OUTPUTFORMAT
      NAME "AGG"
      DRIVER AGG/PNG
      IMAGEMODE RGB
    END

    WEB
      IMAGEPATH "/tmp/ms_tmp/"
      IMAGEURL "/ms_tmp/"
      METADATA
        "wms_srs" "EPSG:3006 EPSG:4326 EPSG:3857"
        "ows_enable_request" "*"
        "ows_title" "Style test"
      END
    END

    PROJECTION
      "init=epsg:4326"
    END

    SYMBOL
        NAME "circle"
        TYPE ELLIPSE
        FILLED TRUE
        POINTS 1 1 END
    END
    SYMBOL
        NAME "square"
        TYPE VECTOR
        FILLED TRUE
        POINTS 0 0 0 1 1 1 1 0 0 0 END
    END
#
# Start of layer definitions
#
    LAYER
        NAME "circle"
        GROUP "ST"
        TYPE POINT
        FEATURE POINTS 10 5 END END
        FEATURE POINTS 15 10 END END
        EXTENT 0 0 20 15
		METADATA
			"wms_title" "Circles"
			"wms_enable_request"   "*"
			"wms_group_title" "Circles"
		END
        STATUS on
        CLASSGROUP "color"
        CLASS
            NAME "circle-color"
            GROUP "color"
            STYLE
                COLOR 255 0 0
                SIZE 15
                WIDTH 1
                SYMBOL "circle"
            END
        END
        CLASS
            NAME "circle-grey"
            GROUP "grey"
            STYLE
                COLOR 50 50 50
                SIZE 15
                WIDTH 1
                SYMBOL "circle"
            END
        END
        CLASS
            NAME "circle-green"
            GROUP "green"
            STYLE
                COLOR 0 255 0
                SIZE 15
                WIDTH 1
                SYMBOL "circle"
            END
        END
    END # Layer
    LAYER
        NAME "square"
        GROUP "ST"
        TYPE POINT
        FEATURE POINTS 10 10 END END
        FEATURE POINTS 15 5 END END
        METADATA
            "wms_title" "Squares"
            "wms_enable_request"   "*"
            "wms_group_title" "Squares"
            "wms_extent" "0 0 20 15"
        END
        STATUS on
        CLASSGROUP "color"
        CLASS
            NAME "square-color"
            GROUP "color"
            STYLE
                COLOR 0 0 255
                SIZE 15
                WIDTH 1
                SYMBOL "square"
            END
        END
        CLASS
            NAME "square-grey"
            GROUP "grey"
            STYLE
                COLOR 100 100 100
                SIZE 15
                WIDTH 1
                SYMBOL "square"
            END
        END
        CLASS
            NAME "square-green"
            GROUP "green"
            STYLE
                COLOR 0 255 0
                SIZE 15
                WIDTH 1
                SYMBOL "square"
            END
        END
    END # Layer
END # Map File