= Plug-in Interfaces = Access controllers respond to a series of standard calls from the experiment controller to create local allocations. These are described in conceptual detail [FeddPluginArchitecture elsewhere on this site] and in a [http://groups.geni.net/geni/attachment/wiki/TIEDProtoGENIPlugin/TIED_CF_plugin_design_spec_v1.0.pdf document about the design of the ProtoGENI plug-in]. This section discussed the calls and their encoding for developers interested in reading and extending existing plug-in code.