in.css

* {
   /* "defaults;" these properties may be overridden by more specific rules */
   label: [PROPERTY];
   label-anchor: 0 1;
}

[ANCHOR_PT IN (1, 3, 6)]  {
    label-anchor: 0 0;
}

[ANCHOR_PT IN (2, 4, 7)]  {
    label-anchor: 0 0.5;
}

in.sld.xml

<?xml version="1.0" encoding="UTF-8"?>
<sld:UserStyle xmlns="http://www.opengis.net/sld" xmlns:sld="http://www.opengis.net/sld" xmlns:ogc="http://www.opengis.net/ogc" xmlns:gml="http://www.opengis.net/gml">
    <sld:Name>Default Styler</sld:Name>
    <sld:Title/>
    <sld:FeatureTypeStyle>
        <sld:Name>name</sld:Name>
        <sld:Rule>
            <ogc:Filter>
                <ogc:And>
                    <ogc:Not>
                        <ogc:Or>
                            <ogc:PropertyIsEqualTo>
                                <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                                <ogc:Literal>6</ogc:Literal>
                            </ogc:PropertyIsEqualTo>
                            <ogc:PropertyIsEqualTo>
                                <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                                <ogc:Literal>3</ogc:Literal>
                            </ogc:PropertyIsEqualTo>
                            <ogc:PropertyIsEqualTo>
                                <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                                <ogc:Literal>1</ogc:Literal>
                            </ogc:PropertyIsEqualTo>
                        </ogc:Or>
                    </ogc:Not>
                    <ogc:Not>
                        <ogc:Or>
                            <ogc:PropertyIsEqualTo>
                                <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                                <ogc:Literal>7</ogc:Literal>
                            </ogc:PropertyIsEqualTo>
                            <ogc:PropertyIsEqualTo>
                                <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                                <ogc:Literal>4</ogc:Literal>
                            </ogc:PropertyIsEqualTo>
                            <ogc:PropertyIsEqualTo>
                                <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                                <ogc:Literal>2</ogc:Literal>
                            </ogc:PropertyIsEqualTo>
                        </ogc:Or>
                    </ogc:Not>
                </ogc:And>
            </ogc:Filter>
            <sld:TextSymbolizer>
                <sld:Label>
                    <ogc:PropertyName>PROPERTY</ogc:PropertyName>
                </sld:Label>
                <sld:LabelPlacement>
                    <sld:PointPlacement>
                        <sld:AnchorPoint>
                            <sld:AnchorPointX>0.0</sld:AnchorPointX>
                            <sld:AnchorPointY>1.0</sld:AnchorPointY>
                        </sld:AnchorPoint>
                    </sld:PointPlacement>
                </sld:LabelPlacement>
                <sld:Fill/>
            </sld:TextSymbolizer>
        </sld:Rule>
        <sld:Rule>
            <ogc:Filter>
                <ogc:Or>
                    <ogc:PropertyIsEqualTo>
                        <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                        <ogc:Literal>7</ogc:Literal>
                    </ogc:PropertyIsEqualTo>
                    <ogc:PropertyIsEqualTo>
                        <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                        <ogc:Literal>4</ogc:Literal>
                    </ogc:PropertyIsEqualTo>
                    <ogc:PropertyIsEqualTo>
                        <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                        <ogc:Literal>2</ogc:Literal>
                    </ogc:PropertyIsEqualTo>
                </ogc:Or>
            </ogc:Filter>
            <sld:TextSymbolizer>
                <sld:Label>
                    <ogc:PropertyName>PROPERTY</ogc:PropertyName>
                </sld:Label>
                <sld:LabelPlacement>
                    <sld:PointPlacement>
                        <sld:AnchorPoint>
                            <sld:AnchorPointX>0.0</sld:AnchorPointX>
                            <sld:AnchorPointY>0.5</sld:AnchorPointY>
                        </sld:AnchorPoint>
                    </sld:PointPlacement>
                </sld:LabelPlacement>
                <sld:Fill/>
            </sld:TextSymbolizer>
        </sld:Rule>
        <sld:Rule>
            <ogc:Filter>
                <ogc:Or>
                    <ogc:PropertyIsEqualTo>
                        <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                        <ogc:Literal>6</ogc:Literal>
                    </ogc:PropertyIsEqualTo>
                    <ogc:PropertyIsEqualTo>
                        <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                        <ogc:Literal>3</ogc:Literal>
                    </ogc:PropertyIsEqualTo>
                    <ogc:PropertyIsEqualTo>
                        <ogc:PropertyName>ANCHOR_PT</ogc:PropertyName>
                        <ogc:Literal>1</ogc:Literal>
                    </ogc:PropertyIsEqualTo>
                </ogc:Or>
            </ogc:Filter>
            <sld:TextSymbolizer>
                <sld:Label>
                    <ogc:PropertyName>PROPERTY</ogc:PropertyName>
                </sld:Label>
                <sld:LabelPlacement>
                    <sld:PointPlacement>
                        <sld:AnchorPoint>
                            <sld:AnchorPointX>0.0</sld:AnchorPointX>
                            <sld:AnchorPointY>0.0</sld:AnchorPointY>
                        </sld:AnchorPoint>
                    </sld:PointPlacement>
                </sld:LabelPlacement>
                <sld:Fill/>
            </sld:TextSymbolizer>
        </sld:Rule>
    </sld:FeatureTypeStyle>
</sld:UserStyle>