The muon reconstruction is based on a modular design in which the input of one module depends on the output of another. This modular design can be schematized by the following picture:

Here, the yellow blocks represent the data while the green blocks represent the reconstruction steps modifying the data. Data comes out of the detector in the form of Raw Data (which can be simulated by the Monte Carlo), and is unpacked into subdetector-specific modules and channels (unpacked data). The unpacked data is reconstructed into hits, which are used as an input for the segment reconstruction. The segment reconstruction creates segments, which are local track segments in one layer of the detector. Segments in different layers, before and after the toroid, are combined in the local track reconstruction, which forms local tracks in the muon system. After this, the global track reconstruction matches these local tracks with information from other subdetectors (calorimeter and inner tracker) to form global tracks and reconstructed muons.