FOUR things are immediately obvious:
First, the clerks selected only a SMALL FRACTION of the original documents for inclusion in the OR. Nearly all battle reports were included, but most of the orders, correspondence, and "routine" day-to-day material was left out.
Second, the clerks sometimes silently EDITED the material as they copied it, so that a document that consists of ten sentences in the original manuscript version might appear in the OR in a shorter form--only six or eight sentences--usually with NO INDICATION that anything is missing!
Third, the clerks sometimes were bamboozled by PROPER NAMES. They could handle "Richmond" and "Smith" but unusual names gave them fits. Somewhere in the OR there is a reference to a Confederate gunboat on the White River. The clerk could not make out the handwriting, nor could he puzzle out what was to him an unfamiliar word. So he transcribed the name of the gunboat as a nonsense jumble of consonants and vowels. I am from Louisiana and when I looked at the original document, it was immediately apparent that the mystery word was "Ponchartrain."
Fourth, the clerks were only human and they made lots of common transcription ERRORS such as "west" for "east," "north" for "south," and so on. They also occasionally misdated items (usually by a year, that is, 1862 for 1863) and placed them out of sequence in the wrong OR volume.
The moral of this story is that the OR was a pioneering masterpiece of historical editing in the late nineteenth century, but by today's more exacting standards it is incomplete and plagued with errors. Use with caution.