### Prime Variable The information below provides a FULL description of this microblock and all of its properties. What information you see and what you can do with it depends on your license and the application you are in, and in some cases, a controller's driver version.
Microblock family | Sys Out microblocks
Icon and symbol |
What it does | This microblock identifies a single specific value from the control program that is representative of the entire control program, such as the current zone temperature. Every control program has a color and a prime variable. Their values are set in the control program logic by the Set Color and Prime Variable microblocks. If these microblocks are not present in the control program, their corresponding values will be zero. It is a good idea to provide meaningful values for these two numbers so that generic graphics or reports will have something meaningful to display for your control program.
#### Properties TIPS Alt+click any value in the WebCTRL® or Field Assistant interface to view property details, including its editing privilege and expression (location path) for use on graphics. You can right-click some properties in the EIKON® Property Editor and select Make editable or Make read-only to determine that property's functionality in your system.
Reference Name RefName | Use the default reference name unless you want a more descriptive name for graphics or network links. Limitations: lower case only limited to 40 characters cannot begin with a number must be unique within a control program