There are no mathematical mistakes here that I am aware of, but many typos, cases of inaccurate wording, etc.:
P.56, second line of last paragraph: "results" should be "result".
P.57, third line of second paragraph: M ⊆ N should be N ⊆ M.
P.57, fourth line of second paragraph: after "intersection of" add "the kernels of".
P.58, next-to-last line of next-to-last paragraph: "maximal" should be "greatest".
P.58, last line: before "closed" insert "nonzero".
P.59, Lemma 2.2: change "unique maximal" to "largest" in the third line of the statement, and in the first line of the proof.
P.60, parenthetical note after end of proof of Corollary 3.3: "This is false for P flat, e.g.," should be "The hypothesis of the above corollary cannot be weakened to merely say that P is flat; e.g., consider".
P.60, Proposition 3.4, last line of (5): "(row-finite)" should be "(column-finite)".
P.62, second line of proof of Proposition 4.2: Where I say "Using Lemma 2.2 and Corollary 3.3", a clearer explanation would be "Using Corollary 3.3 (the local closure hypothesis of which holds by Lemma 2.2)".
P.65, last line of middle paragraph: "is minimal in" should be "is the least element of", and in the next line, "minimal" should likewise be "least".
P.65, first line of next-to-last paragraph: "assymmetric" should be "asymmetric".
P.66, last line of first paragraph of section 7: "ringconstructions" should be "ring constructions".