Under what conditions will X-WOPI-OverwriteRelativeTarget be set to true?

[tylerbutler]

X-WOPI-OverwriteRelativeTarget indicates that if the filename we pass with PutRelative already exists, overwrite the file. Otherwise, hosts should return a 409 error with a suggested new file name. In Excel there is a checkbox that gives the user the option to do this on Save As; this is the only place today that this header is set.