The $Y compiler directive determines whether Delphi builds symbol definition and reference information, as used by the Delphi browser and code explorer.
By default, Delphi builds just the definitions, and not the references.
The references are the users of the symbols.
The overheads for keeping symbol information are minimal.
The allowed values are :
|$YD || = Defs On , Refs Off|
|$Y- || = Defs Off, Refs Off|
|$Y+ || = Defs On , Refs On|
$Y only works when $DebugInfo and LocalSymbols are On.