I have a few suggestions about the approach of the Rambam about documents. one is that he meant what he wrote. there is a tendency to explain away what people find that they do not like e.g., kidushei keseph [Marriage by money]. But i think when he wrote [Laws of Witnessing 3:4] all monetary documents are DeRananan he meant it and the question of the Ramban from documents of gitin and kidushin do not apply. i think also in a weaker vein that there is a connection between this decision and the fact that the law in gitin and documents that witness that see the act cause the act to become real, not the witnesses on the document. while on one hand this seems weak because a get is a document without witnesses at all just by the husband writing the words you are allowed to any man, still the act of divorce is not valid until the witnesses see it. However, I still see what might be a connection here. Another suggestion is for Bava Metzia page 13a. I believe the Rambam explains Rav Asi there like the Rabbainu Chanael that the document of kinyan there is what he explains in laws of loans 23:5 a document in which there is a kinyan for from the time they made the kinyan, there was already a lean on all properties of the borrower. This issue was a debate on page 13 where Rav Asi [or Rav Ashi in the version of Rabbainu Chananel] claimed R. Meir holds a document of kinyan is valid immediately and presumably this applies to the sages also. But, Abayee holds the witnesses on the document cause it and the loan (or any other monetary obligation in it) to be valid immediately. (That sounds like R Meir that the witnesses on a divorce document cause it to be valid when it is given to the woman.) {The Rambam applies this to a different argument. Page 13 deals with a document that was lost, the found by a stranger. But the Rambam applies the document of kinyan there to apply to the law of writing a document of a kinyan to a borrower even when the lender is not with him.} The approach of Abayee I think is not the opinion of the Rambam because he seems to decide like RavAsi.---------------------------------------I have a few suggestions about the approach of the רמב’’ם about שטרs. one is that he meant what he wrote. there is a tendency to explain away what people find that they do not like e.g., קידושי כסף. But i think when he wrote [Laws of Witnessing 3:4] all monetary שטרs are דרבנן he meant it, and the question of the רמב''ן from שטרs of גיטין and קידושין do not apply. i think also in a weaker vein that there is a connection between this decision and the fact that the law in גיטין and שטרs that witness that see the act cause the act to become real, not the witnesses on the שטר. while on one hand this seems weak because a get is a שטר without witnesses at all just by the husband writing the words you are allowed to any man, still the act of divorce is not valid until the witnesses see it. However, I still see what might be a connection here. Another suggestion is for בבא מציעא י''ג ע''א. I believe the רמב’’ם explains רב אסי there like רבינו חננאל that the שטר of אקנייתא there is what he explains in ה' טוען ונטען פרק ג' הלכה ד' : a שטר in which there is a קניין is valid from the time they made the קניין since there was already a שיעבוד on all קרקעות of the borrower. This issue was a debate on page 13 where רב אסי [or רב אשיi in the version of רבינו חננאל] claimed ר' מאיר holds a שטר of קניין is valid immediately and presumably this applies to the sages also. But, אביי holds the witnesses on the שטר cause it and the loan (or any other monetary obligation in it) to be valid immediately. (That sounds like ר' מאיר that the עדי חתימה כרתי.) {The רמב’’ם applies שטר אקנייתא to a different argument. Page י''ג deals with a שטר that was lost, then found by a stranger. But the רמב’’ם applies the שטר of אקנייתא there to apply to the law of writing a שטר of a התחייבות to a borrower, even when the lender is not with him.} The approach of the רמב’’ם I think is not like אבייbecause he seems to decide like רב אסי.