Using External Editor

I have heard that there is the way to inform Delphi IDE one of its
files has been externally updated (DDE ?) . I'm using my own editor
and most of the time I use DCC to compile, but time to time I need to
run IDE tomake changes in forms, properties and so. Is there any
protocol how to inform Delphi that one (or more) of used source files
has been updated externally ?