example of simple SLD file accepted by OpenLayers

cartaro_train_sld

<?xml version="1.0" encoding="UTF-8"?>
<StyledLayerDescriptor version="1.0.0" xsi:schemaLocation="http://www.opengis.net/sld StyledLayerDescriptor.xsd" xmlns="http://www.opengis.net/sld" xmlns:ogc="http://www.opengis.net/ogc" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <NamedLayer>
    <Name>trainsample</Name>
    <UserStyle>
      <Name>trainsample</Name>
      <FeatureTypeStyle>
        <Rule>
          <Name>Bridges</Name>
          <ogc:Filter>
            <ogc:PropertyIsEqualTo>
              <ogc:PropertyName>field_type_value</ogc:PropertyName>
              <ogc:Literal>bridge</ogc:Literal>
            </ogc:PropertyIsEqualTo>
          </ogc:Filter>
          <LineSymbolizer>
            <Stroke>
              <CssParameter name="stroke">#ff0000</CssParameter>
              <CssParameter name="stroke-width">3</CssParameter>
              <CssParameter name="stroke-linejoin">bevel</CssParameter>
              <CssParameter name="stroke-linecap">square</CssParameter>
            </Stroke>
          </LineSymbolizer>
        </Rule>
        <Rule>
          <Name>zug</Name>
          <ogc:Filter>
            <ogc:Literal>1</ogc:Literal>
          </ogc:Filter>
          <LineSymbolizer>
            <Stroke>
              <CssParameter name="stroke">#ffffff</CssParameter>
              <CssParameter name="stroke-width">1.26</CssParameter>
              <CssParameter name="stroke-linejoin">bevel</CssParameter>
              <CssParameter name="stroke-linecap">square</CssParameter>
              <CssParameter name="stroke-dasharray">5 2</CssParameter>
            </Stroke>
          </LineSymbolizer>
          <LineSymbolizer>
            <Stroke>
              <CssParameter name="stroke">#000000</CssParameter>
              <CssParameter name="stroke-width">1.26</CssParameter>
              <CssParameter name="stroke-linejoin">bevel</CssParameter>
              <CssParameter name="stroke-linecap">butt</CssParameter>
              <CssParameter name="stroke-dasharray">5 5</CssParameter>
            </Stroke>
          </LineSymbolizer>
        </Rule>
      </FeatureTypeStyle>
    </UserStyle>
  </NamedLayer>
</StyledLayerDescriptor>