an error code to the thread&#39;s error queue. It signals that the error of reason code <b>reason</b> occurred in function <b>func</b> of library <b>lib</b>, in line number <b>line</b> of <b>file</b>. This function is usually called by a macro.</p>

<p>ERR_add_error_data() associates the concatenation of its <b>num</b> string arguments as additional data with the error code added last. ERR_add_error_vdata() is similar except the argument is a <b>va_list</b>. Multiple calls to these functions append to the c