'Ctl' is the file type of LabVIEW controls. Controls are stored either in their parent vi or in dedicated files. The latter helps to define similar controls on different VIs.
You define user-specific controls by right-clicking a control and choosing Advanced/Customize. This opens the control editor, where you can change the control.
Attention! Creating a control on a VI's Frontpanel [FP] from a specified *.ctl file copies this control into the FP, but does not maintain a link to the *.ctl file. Any changes applied to the *.ctl afterwards are not propagated to the VIs FP. Use Type Definitions instead if you need to maintain consistancy between different control instances.
See Also
Ctl
