Data instances can have a “quantity type”. In effect, visualization is simpler, and it enables the compiler to prevent quantity errors in your program.

Examples of Quantity types are:

• Density
• Pressure
• Energy
• Volume
• Mass
• Time

When you add variables of a floating-point type that represents a quantity, it is important to state the quantity type.
The compiler deduces the quantity type for the result of a calculation or expression. In effect, when you assign a value to the float, the compiler analyzes the quantity types and shows when there is an error such as

Volume: = Density

In addition, all data in a COPP component is stored in SI-units. A HMI convert between locally used units. For example, when the operator changes a set point.