[Description] Gets the string representing the extension part of the file. [Name] 
Extension
A t t r i b u t e s
C r e a t i o n T i m e
E x i s t s
E x t e n s i o n
F u l l N a m e
L a s t A c c e s s T i m e
L a s t W r i t e T i m e
N a m e