For each API call issued, LAN Server returns a numeric code telling the application whether the function was successful or why it failed. (Unless noted otherwise in the Syntax sections, the return function type is API_FUNCTION.) To make programming easier, each of these codes also is assigned short, descriptive text, called a symbolic constant in this book. For example, the symbolic constant NERR_Success is equivalent to a return code of 0, a successful completion. (A symbolic constant is the same as a manifest or manifest constant, terms used in previous releases.)

The text for the symbolic constant is defined in the header files (also called include files in previous releases). The header files provided by LAN Server are installed in the \IBMLAN\NETSRC\H subdirectory by default, although this can be changed.

Your application must include any header files that contain symbolic constants used by your application. Although an application typically uses more than one header file, each header file needs to be included only once, usually at the beginning of the program.