| Siebel Product Administration Guide > Configuration Links >  Creating a System Variable Configuration Link
 A system variable link lets you obtain the value of the following system variables and use it to write constraints: 
TODAY. Provides the system date. The data type is Date and can be used for date computations.
WHO. Provides the user's login name. The data type is Text. 
 To create a system variable link 
Navigate to the Administration - Product screen.
Select and lock the desired customizable product or product class.
Navigate to the Linked Items view for the Work Space version.
In the Link Definitions list, add a new record and complete the necessary fields, described in the following table. 
    |  |  |  
    | Name | Enter the name of the link. Use this name to refer to the link when you write constraints. This field is required. |  
    | Keyword | Select either TODAY or WHO. This field is required for system variable links. |  
    | Description | Optionally, enter a description of what the link does. This description is not displayed to customers. | NOTE:  Leave all the other fields blank. They are only used for business component links.  |