If you want to create a [JSup graphic windows#Window type|popup window] to control many items (one at a time) ''linkable'' [JSup tag|tags] would be very useful.

A ''linkable'' [JSup tag|tag] (named <TT>A</TT>, for example) has the ability to be linked to another [JSup tag|tag] (named <TT>B</TT>, for example), so <TT>A</TT> and <TT>B</TT> have always the same value. 
If you assign a new value to <TT>A</TT> the same value is assigned to <TT>B</TT>; the same if you assign a value di <TT>B</TT>: that value is written to <TT>A</TT> also.

To build a [JSup graphic windows#Window type|popup window] to control many items two ''linkable'' tags would be used:
 * a tag (<TT>Status</TT>) that will be linked to the tag that provide the status of the item to control;
 * a tag (<TT>Command</TT>) that will be linked to the tag that send commands to the item to control.
Before to show the [JSup graphic windows#Window type|popup window] to control the item 21 (for example) a piece of [JSup Code|code] have to link the tag; for example:
<code>Status.linkTo( Item21_Status );
Command.linkTo( Item21_Command );
ItemControlPopup.show();</code>

A ''linkable'' [JSup tag|tag] can be linked to a single [JSup tag|tag] at a time.

''Linkable'' [JSup tag|tags] are normally defined in the [JSup domains|User domain] (for a purpose like in the example above).