The NWScript engine uses this file: x_nwscript.nss as reference to know: - The internal engine structures (effect, event, location…) - The internal functions (their implementation is hard-coded) It also declares many constants and #include other scripts that do the same, they are all in this ERF: https://nwn.sinfar.net/res_list.php?erf_id=1 This x_nwscript.nss is loaded before compiling a script so everything that they contains
All base NWScript functions and constants are avaiable, their original documentation can be found here: https://nwnlexicon.com/, but some of them have been changed (mostly extended) so you should first check if they are in the reference below.
Additionally, Sinfar has its own set of internal functions (and constants), they are in this those file: x_sfscript.nss and x_sfscript_const.nss. Feel free to try them, they should be crash-safe so at worst they will do nothing or cause a script error.
Here are the documented functions: