Returns a description of the extension the specified index position (zero based index).
ERROR: Syntax information about ILibraryLookupInfo.ExtensionDescription may not be in D:\ArcGIS\DotNet\ESRI.ArcGIS.SystemUtility.dll
[C++]
HRESULT ExtensionDescription(
long* lIndex,
BSTR* sDesc
);
[C++]Parameters
lIndex [in, out] lIndex is a parameter of type long sDesc [out, retval] sDesc is a parameter of type BSTR