Is translated into nothing. This tag is often used between {IF...} tags if no action is to be taken.
Example of Use
{IF-CUSTOMER-LOGGED-IN-BEGIN} (Begin check to see if the customer is logged in.)
Hello, you are logged in! (Display a greeting.) {ELSE} (Otherwise...) {NULL} (If the customer is not logged in, do nothing.) {IF-CUSTOMER-LOGGED-IN-END} (End check to see if the customer is logged in.)
Source Code
Source Code Updated:
When a web page using a template that contains this QuickCode Tag is viewed in the storefront, the {NULL} QuickCode Tag is changed into the source code below prior to the web page being displayed.
{NULL}
Example of Use 
Source Code