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Hide from FOIA searches.
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It may have previously been on a paper document that was scanned and OCRed. (less likely, since other 'm's weren't converted to 'rn's.)
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A deliberate reference to Comey's standing-in-corn-fields Twitter pictures. It's also possible that during Comey's career he was fond of farming analogies to describe the progression of investigations and Q & Co are needling him with this.
There is no clear consensus yet.