#### 13.4.1 refdes attribute

This attribute is used to specify the reference designator to a particular instantiated component. It must be on ALL components which have some sort of electrical significance. This attribute can also be on the inside of a symbol (it will be promoted, i.e. attached to the outside of the symbol, if it is visible) to provide a default refdes value (such as `U?`). Usually this attribute is composed by a prefix (`U` for example) and a number (different for each component).

Examples:

    refdes=U1
    refdes=R10
    refdes=CONN1