To track, also known as ground beam \ geosyncline iron \ base slot iron \ bar platform \ T-slot to track, for large equipment assembly / test \ welding and inspection 
 To track the main purposes: a fixed point of the device design, stitching, mainly for large equipment assembly, testing, welding and inspection. 
 Used to track the advantages: not made large-scale platform, which saves material costs, but also takes up very little space to track specifications: specifications according to the demand-side or two sides agreed to make drawings of production and processing.