The PreInit Table is built by the user (using Language Environment supplied macros). It identifies the set of routines that the user will be invoking within a given pre-initialized environment. Language Environment uses this table to pre-load these routines during PreInit initialization and to identify the set of Language Environment languages that may be used by this pre-initialized environment.

The assembler Driver program is a user-written program that is used to control a pre-initialized environment. It consists of a series of calls to the CELQPIPI service, to initialize a PreInit environment, invoke user routines, and terminate a PreInit environment.

The CELQPIPI is a service provided by Language Environment to support 64-bit pre-initialized environments. All of the operations that are required to use a PreInit environment are accessed through calls to this service.