The use of null-terminated character strings as opposed to vms string descriptors presents one of the greatest differences between the PI Toolkit (for OpenVMS) and the PI-API functions. All strings passed to PI-API functions are expected to be null-terminated. All functions that return a string expect the length of the caller-supplied character buffer to be passed in a length parameter, with the returned string being null-terminated and truncated, if necessary, to fit the specified length.
In cases where functions can fail, a status value is returned by the function. In other cases, the function has a void return or returns data, such as with pitm_systime.