Utility class containing constants. 
            Represents how to update links to other workbooks when the workbook is opened.
            
| Field Summary | 
| const  Number | USER_SET |  | 
| 
            Prompt user to update.
             | 
| const  Number | NEVER |  | 
| 
            Do not update, and do not prompt user.
             | 
| const  Number | ALWAYS |  | 
| 
            Always update.
             | 
 
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- Field Detail- USER_SET- 
const Number USER_SET - 
            Prompt user to update.
            
 
 - ALWAYS- 
const Number ALWAYS - 
            Always update.