High level triggers must process data in real time and so must run very quickly. In this example, the muon system searches for track segments in one technology in the region of a trigger indicated by another technology. The data is read from the raw data format and processed by a trigger algorithm.
The algorithm uses the digit container to fetch data only from a restricted region. The algorithm identifies the relevant modules (e.g. chambers) within the technology to be processed. It loops over modules and requests the data for each from the container. The container unpacks and returns the data as requested.
Strict time requirements are met by only unpacking data in (and possibly near) the region of interest.