A flexible instrument control and data storage/management system and method for representing and processing assay plates having one or more predefined plate locations is disclosed. The system utilizes a graph data structure, layer objects and data objects. The layer objects map the graph data structure to the data objects. The graph data structure can comprise one node for each of the one or more predefined plate locations, wherein the nodes can be hierarchically defined according to a predefined plate location hierarchy. Each node can be given a unique node identifier, a node type and a node association that implements the predefined plate location hierarchy. The layer objects can include an index that maps the node identifiers to the data objects.