DDCond Manual

Experimental setups in High Energy Physics are highly complex assemblies consisting of various detector devices typically called subdetectors. To properly interpret the electronic signals which form the response of particle collisions inside these subdetectors other auxiliary data are necessary. These auxiliary data typically are time dependent - though normally at a much longer scale than the event data itself. The conditions part of the $DD4hep$ toolkit, called DDCond , addresses the management and the access of such conditions data. The Manual describes a solution, which pools groups of these time dependent data according to its validity. This approach firstly allows to quickly access all relevant data for a given particle collision. efficient caching mechansims and allows to quickly determine which data items need to be accessed from a persistent medium. The design is strongly driven by easy of use; developers of detector descriptions and applications using them should provide minimal information and minimal specific code to achieve the desired result.