Another "~" question

Ok, by now we all know that the leading "~\$" of a filename indicates that the file is a temporary one and should be removed automatically by Solidworks.  We also know that if you open that offending file with Notepad, it will display the name of the user (login name) that has, or had it open (if Solidworks crashes before it can remove the file).  Well here's one that I cannot find…

What does it mean when a tilde "~" comes just before the file extension (e.g. filename.~sldprt)?

Anxiously awaiting a reply.

Joe

SolidworksGeneral