TV_3DVECTOR

This convenient structure holds 3 variables and is primarily used to hold a point in the 3D world. It is used intensively throughout the engine.

DECLARATION

VB.NET	Public Structure TV_3DVECTOR Public x As Single, y, z End Structure
C++	public: struct TV_3DVECTOR { float x, y, z; };
C#	public struct TV_3DVECTOR { float x, y, z; };

VB.NET	`TV_3DVECTOR(ByVal x As Single, ByVal y As Single, ByVal z As Single) TV_3DVECTOR()`
C++	`TV_3DVECTOR(float x, float y, float z) TV_3DVECTOR(void) TV_3DVECTOR(TV_3DVECTOR*)`

C#.NET

TV_3DVECTOR vec1 = new TV_3DVECTOR(0.5f, 0.5f, 0.5f);

You can perform addition, subtraction, multiplication and division operations on TV_3DVECTOR objects using the standard +, -, /, * symbols
For more information about vectors in general you might want to check out this wiki page about Vector space