DB-Library uses two main control structures: LOGINREC and DBPROCESS.
Client-Library uses three control structures: CS_CONTEXT, CS_CONNECTION, and CS_COMMAND.
The CS_CONTEXT structure defines an application context, or operating environment.
The CS_CONNECTION structure defines a client/server connection within an application context. Multiple connections are allowed per context.
The CS_COMMAND structure defines a command space within a connection. Multiple command structures are allowed per connection.
The CS_CONTEXT structure has no real DB-Library equivalent but stores information similar to that stored in DB-Library hidden global variables.
Together, the CS_CONNECTION and CS_COMMAND structures roughly correspond to the DBPROCESS structure.
Unlike DB-Library structures, Client-Library control structures are truly hidden: The structure names are defined in Client Library’s public header files, but the fields are not.
In this document, CS_CONTEXT structures
are also called “context structures,” CS_CONNECTION structures
are also called “connection structures,” and CS_COMMAND structures
are also called “command structures.”