Francois Pinet Myoung-Ah Kang Frédéric Vigier Spatial Constraint Modelling with a GIS Extension of UML and OCL: Application to Agricultural Information Systems. 160-178 2004 conf/metainformatics/2004 Metainformatics http://dx.doi.org/10.1007/11518358_13 db/conf/metainformatics/metainformatics2004.html#PinetKV04