The ATLAS readout identifiers are described in the ATLAS note ATL-SOFT-2001-004. Each detector element is specified by a hierarchial list. For example, 7/BIL/-3/5/MDT/0/2/4 refers to tube 4 in layer 2 of MDT multilayer 0 in phi sector 5 and eta sector -2 of the long barrel inner layer of the muon spectrometer (WBS item 7). Chambers can be identified by keeping part of this hierarchy.
It is natural to define a class or class hierachy to carry these values and check their validity. In the present ATLAS release, ther are such classes for each muon technology but they do not follow the conventions in the above note. Steve Goldfarb has promised to rectify this.