Tag aliasing is a concept which is particularly important in RSLogix 5000. The reason is that most RSLogix 5000 based Programmable Logic Controllers (PLCs) aren’t able to save tag descriptions within their memory. If the program is lost & needs to be uploaded from the controller, it will be restored without a single description. However, if you’re working with Studio 5000 v21 or above, your PLC will most likely have the capability to store the descriptions you add into your program.
https://www.solisplc.com/tutorials/rslogix-5000-tag-structure-creating-alias-tags-for-plc-input-output-modules-point-io-studio-5000