In early 2006 the OGC members approved the OpenGIS GML Simple Features Profile.
The WFS specification defines interfaces for describing data manipulation operations of geographic features.
The client generates the request and posts it to a web feature server using HTTP.
For both versions of the WFS specification, an arbitrary number of other encodings can also be defined, in addition to the required GML 2.1.2 or 3.1.1 format (for 1.0.0 and 1.1.0 respectively).
GML 3.1.1 contains encoding support for more advanced geometric representations: curves, surfaces, multi-dimensions (time, elevation, multi-band imagery).