[racket] CRLF indicator in bottom right of DrRacket

Dear list members,

When I open one of the files I'm editing in DrRacket there is a "CRLF"
displayed with an orange background in the lower right side of DrRacket
just before the current line and column numbers..  This only happens with
this one file.  When I open other files the CRLF indicator doesn't appear.
 At first I thought it indicated that CRLF was the line terminator, but
CRLF is the line terminator in all the files I'm editing and the indicator
only shows up for this one file.

If I open the file in a tab the CRLF indicator always appears, but if I
 select and copy the file from one tab to a second tab the indicator
doesn't appear in the second tab.

Can someone tell me what this indicator is?

Thanks,
Harry Spier
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