Trainz Containers
From TrainzOnline
Trainz Containers are data types which serve to group data definitions of one sort or another that is important to the software system. The data might be in list form (all the attachment points for passengers on a train station platform) or a table of related parameters which must work together (Engine specifications of one kind or another). In some cases it is an ordered list (kuid-tables in a layout for example) or table.
The Category:Config Container lists most containers in the software system.