How does an alias work in grunt browning?

I've read the official documentation on alias

grunt browning options configuration but still don't fully understand the semantics of the array that is expected to provide as a value.

FROM

alias: ["pathA:pathB"]

      

        
        
        
      

    

What goes to the left of the colon and what goes to the right?

And what does it mean? (grunt-browserify doesn't complain, but what does it do?)

alias: ["pathA:"]

      

        
        
        
      

    

Are there other alias configurations such as the latest that are not documented?

Thank you so much!