Reference

All functions
pgf_collection_bbox()	Get collection bbox
pgf_collection_crs()	Get collection crs
pgf_collection_description()	Get collection description
pgf_collection_feature()	Get collection feature
pgf_collection_features()	Get collection features
pgf_collection_geometry_type()	Get collection geometry type
pgf_collection_properties()	Get collection properties
pgf_collections()	Get collections
pgf_function_description()	Get function description
pgf_function_parameters()	Get function parameters
pgf_function_properties()	Get function properties
pgf_function_result()	Get function result
pgf_functions()	Get functions