A domain gate is an entry point or interface to a domain. It can be called by any authorized caller who needs to use some function provided by the domain.
A number of domain functions are available through the exit programming interface (XPI). For details, see the CICS® Customization Guide.
In practice, every domain has several gates. Each gate has a 4-character identifier; the first two characters are the identifier of the owning domain, and the second two characters differentiate between the functions of the domain’s gates. Here, for example, are two of the dispatcher (DS) domain’s gates: