The event builder has the ability to write its output directly to a file. It is more common to put the data into a shared memory buffer manager. The buffer manager allows several processes to look at the data stream. The CODA user has the choice of one of two buffer managers. The previous version of CODA (1.4) and early installations of CODA 2 used a system called the data distribution system or DD. This buffer manager originated with Christoph Witzig (formerly Brookhaven) who was not a member of the CODA group. At the time that we were writing CODA 1.4 the DD system looked like a good match for CODA. Unfortunately, in some applications, the DD system introduced severe instability problems. (The system does not behave well if one of the attached processes exits unexpectedly. This is not a problem in a small system where all the processes can be restarted.) A new buffer manager was developed for CODA 2. This system is called the event transfer or ET system. The ET system is written using POSIX threads and pthread mutexes and is much faster and more stable than the DD system. It is therefore the system of choice for new installations.