+--------+       
Alias:     | $alias | ------------+
           +--------+             |                          
                                  |
                                 \|/
           +--------+       +----------+       +---------+
Variable:  |  $var  | ----> | Variable | ----> | Content |
           +--------+       +----------+       +---------+
                                 /|\                   
                                  +--------+          
           +--------+       +----------+   |          
Reference: |  $ref  | ----> | Variable | --+          
           +--------+       +----------+