Required Header Files
You will note in the initial code segments that, apart from the standard header files, we include the SafeNet ProtectToolkit-C set of required library files.
#include "cryptoki.h"
#include "ctextra.h"
#include "ctutil.h"
#include "chkret.h"
Whereas cryptoki.h is the required PKCS#11 header, the remainder implement some of the advanced or extended features of the SafeNet ProtectToolkit-C implementation, such as error feedback.
Next, see Runtime Switches.