A valuable part of OATs is the extensive library of functions and function blocks - currently over 650, still growing.
There are not only the standard PLC functions and function blocks mentioned in the IEC 61131 -3, but many other ready to use - DayOfWeek, Deadband, file handling, Hysteresis, Noise, PID, PT1, PT2, scaling, splines, StopWatch, ThreePoint controller, IEC 61131 -5 communication function blocks, MODBUS/TCP client and server, a small Fuzzy Control library and more.
Nearly all function blocks are available in the PLC simulation too. Those which handle I/O modules or networking are replaced by similar dummy function blocks.
OATs libraries have a fine granularity. Specialised or reduced libraries can be build for controllers with limited storage resources.