%GET{}%. No output is shown, e.g. %SET{}% resolves to an empty string. The %SET{}% and %GET{}% variables are handled by the SetGetPlugin.
%SET{ "name" value="..." remember="1" }%
|  Parameter |      Description | Default | 
|---|---|---|
 value="..."  |      Value of variable. Escape double quotes with backslash. | (required, may be empty) | 
 remember="1"  |      If set, the variable will be stored persistently so that it can be used later in any TWiki topic. See important notes. |  "0"  |      
 "name"  |      Name of variable. Alphanumeric characters, dashes and underscores can be used. | (required) | 
%SET{"lunch" value="Sushi"}% - see more examples.