The LOCALINFO tag displays a value from the specified field for the user's/processing library's site code. For single servers, the LocalInfo row would be Lending for Lending requests and either ILL or the specific delivery location code for that borrowing user.
For shared servers, the LocalInfo row would be the processing site code for Lending requests and either the processing site code or specific delivery location code for that borrowing user.
The LocalInfo table stores contact information for your institution, allowing you to use tags in your web interface. Should any contact information change, you would only need to update the one table in the Customization Manager.
An example of how this tag would display in the HTML:
<#LOCALINFO field="SystemName">