Prototype and description of the function getntvrefequiv()

(Function of the unlock requiring group "NTv2 Transformations")


Determination of an NTv2 equivalent Helmert/Molodensky Reference System.

Prototype of the DLL function in C++ syntax (attend lower case!):
extern "C" __declspec(dllimport) unsigned long __stdcall getntvrefequiv(
     unsigned short wRefSys,
     unsigned short *wRefNtvE);

Prototype of the DLL function in Visual Objects syntax:
_DLL function getntvrefequiv(;
     wRefSys as word,;                     // 2 Byte
     wRefNtvE ref word);                   // 4 Byte
as logic pascal:geodll32.getntvrefequiv    // 4 Byte

The function returns for the NTv2 Reference System wRefSys an equivalent
Helmert / Molodensky Reference System in wRefNtvE.

The parameters are passed and/or returned as follows:
wRefSys     Geodetic Reference System, belonging to a NTv2 grid file, for
            which an equivalent Helmert / Molodensky Reference System is
            to be determined. The available Reference Systems are
            specified in the list "Coordinate Reference Systems".

wRefNtvE    The number of the determined equivalent Helmert / Molodensky
(ref)       Reference System. The number of the geodetic Reference System
            is returned by reference.
            The function returns the number 5000, if in special cases no
            equivalent Helmert / Molodensky Reference System is available.

returnVal   In case of an error the function returns FALSE, otherwise TRUE.

This function is a component of the unlock requiring function group
"NTv2 Transformations". It is unlocked for unrestricted use together with the
other functions of the group by passing the unlock parameters, acquired
from the software distribution company, trough the function setunlockcode().
Without unlocking only a few function calls for test purposes (shareware
principle) are possible. It should be noted that in addition the function
group "Coordinate Transformations" must be unlocked.