Styled Layer Descriptor profile of the Web Map Service : DescribeLayer
http://www.opengeospatial.org/standards/sld
Defining a user-defined style requires information about the features being symbolized, or at least their feature/coverage type. Since user-defined styles can be applied to a named layer, there needs to be a mechanism by which a client can obtain feature/coverage-type information for a named layer. This is another example of bridging the gap between the WMS concepts of layers and styles and WFS/WCS concepts such as feature-type and coverage layer. To allow this, a WMS may optionally support the DescribeLayer request.
DescribeLayer method has been thought to be a better approach than overloading the WMS capabilities document even more.
For each named layer, the description should indicate if it is indeed based on feature data and if so it should indicate the WFS/WCS (by a URL prefix) and the feature/coverage types. Note that it is perfectly valid for a named layer not to be describable in this way.*
This feature was funded by: Pays de Pontivy This feature was developed by: 3Liz