Let's try running some filters against our OGC:WFS at http://127.0.0.1/cgi-bin/mapserv.exe?map=/ms4w/apps/ms-ogc-workshop/service/config.map
Before running filters, we can find out the 'schema' of the feature type, with http://127.0.0.1/cgi-bin/mapserv.exe?map=/ms4w/apps/ms-ogc-workshop/service/config.map&version=1.0.0&service=WFS&request=DescribeFeatureType&typename=rivers
Here's an example which equates to 'NAME="Great Bear"'
Here's an example which equates to 'NAME="Japura" && SYSTEM="Amazon"'
Here's an example which equates to 'NAME="Japura" OR NAME="Niger"'
Here's an example which equates to 'NAME !="Japura"'