dar -d -- diff of file data or metadata?

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Hi,
I've been relying on dar since I first started doing backups (years ago).
And I've rarely touched anything else. Eventually, I found myself having
to perform a final differential backup of my data because my filesystem
was badly corrupted by an accident.
When I did this, I noted that some files, which I knew to have been
affected, dar reported as identical to the originals in my full backup.

I'm concerned that when I run "dar -d" on my backups to ensure that the
metadata and file-data is identical to the data on disk I will be only
comparing the metadata, not the file-data.

The rational for running "dar -d" vs. "dar -x; diff original/ backup/" is:
Not everyone has enough space remaining on their disks to decompress the
archives that they create.

I have upgraded my disk capacity and count over the years and have used
dar each time. I assumed, perhaps foolishly, that dar diff'ed the
metadata AND filedata.

Please tell me which way it is. And perhaps clarify it inside of the man
page.

Thanks,
David
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