It is possible to choose between the different functionalities. In the following, a distinction is made between the range of functions that have been extended by the POSIX functionality and the range of functions available in BS2000 (without POSIX), which represents the BS2000 functionality.
The C library functions which provide the BS2000 functionality form the basis of the library. In addition, the extra functions of the C library provide the POSIX functionality. Therefore, in choosing the extended functionality, you can use all functions of the library, i.e. both the BS2000 functions and additional additional functions, for example all XPG4 Version 2-conformant functions.
A small number of functions have different variants in BS2000 and in POSIX. These are, on the one hand, the functions for input/output and file accesses (for a list of these functions, see "File processing") and, on the other, time functions, signal processing and interrupt functions, plus the clock() and system() functions.
Below is described for both types of functionality which variant of the respective functions is used.