The original article is called "Closing The Book on Pearl Harbor" by Stephen Budiansky and is in the April, 2000 issue of Crytologia. Stephen Budiansky also wrote "Battle of Wits: The Complete Story of Codebreaking in World War II" which though I have not read it, I did look at portions of it on Google Books when I was researching the "Big Leak" paper I did on the leak of the Rainbow 5 Plan to the Chicago Tribune on December 4th, 1941. The article was actually one of my primary sources on the background I put forth in that essay. (Pretty good essay I thought, though I admit that I could not identify who the source of the leak was.)
So Stinnett does mention the AN-1 after all, just under a different name, which is what I suspected was going on after we went back and forth on this a few times. Also he mentions in his notes that the 5-Numeral or AN-1 to match up the terminology was translated in 1945 and 1946 (p. 334). Too late for Pearl. The only way to verify this would be go the the National Archives and look at the RG 457 documentation. The Japanese decrypts in question are in boxes 286-516 so talk about something that would take a while. :)
What is interesting is that Stinnett says that all these codes were were easily read during this period then points out in his notes that the AN-1 was not translated until 1945. Strange oversight. But again, I'm not criticizing his theory, I just find it interesting that this unbroken code is not more predominant in his research. That doesn't necessarily mean anything.
As to Wiki not mentioning AN-1, I again urge you not to use Wikipedia as a primary source. Just because it's not in it, doesn't mean it does not exist. I had to do some digging to make this connection and I never once looked at Wikipedia to do it.
I found this article in my searching which ties the terminology together and is a pretty well researched essay so far. I'm about half way through it at the moment and will get back to it tonight after my son's graduation party.
Decoding Pearl Harbor: USN Cryptanalysis and the Challenge of JN-25B in 1941
In Stinnett's defense, here are his exact words, which you referenced:
Beginning in chapter 4, page 46-47:
"Hitokappu Bay, an inlet on Etorofu Island in the Kurile Islands group, was the assembly location for six carriers of the First Air Fleet -- the offensive power of the Pearl Harbor raid.
Joining the carriers in the anchorage were its support force of two battleships, two heavy cruisers, eleven destroyers, and three "I" type submarines, plus the crucial supply train of seven tankers."Several warships committed a serious radio security breach during their sortie to the Hitokappu Bay anchorage: each transmitted coded movement reports -- reports that could be read by American naval cryptologists in Washington, according to Albert Pelletier one of the Navy's top cryppies at Station US" [Station US was in Wash DC]. Footnote 18
Now, turning to your referenced page 334, we find footnote 18:
"During 1941 apparently 90 percent of the Japanese navy's coded movement reports were decoded and translated in Washington at Station US, according to an article written by US Navy cryptologist Captain Al Pelletier in Cryptolog, Summer 1992 issue, p.5."But Duane Whitlock, a 1941 raido traffic analyst at Station CAST (the US Navy's cryptographic center for the US Asiatic Fleet on Corregidor island) said in a telephone interview with the author that his unit was not provided the means to decode Japan's ship movement code.
" 'If Washington was reading Japan's ship movement code in 1941, that's news to me,' Whitlock said in the interview. 'We did not have the solution to the ship movement code at CAST' (Whitlock telephone interview, June 1999, notes in author's file)."For Japanese radio orders directing warships to standby locations, see the Special Research Navy (SRN) file in RG 457, and the Daily Chronology of Station H [Hawaii], dated Nov. 15-30, 1941 in RG 38, MMRB, at Archives II.
"The reader is reminded that the English text in the SRN translations contained in RG 457 was "trans" in 1945 and 1946; the original intercepts were obtained in 1941.
There is no reliable evidence, found by the author, that establishes how much of the 5-Num text could be deciphered, translated, and read by naval cryptographers in 1941."
In summary: In 1941, 90% of the Japanese Navy's SM movement reports were decoded and read in Washington, but there's no reliable evidence showing how much of 5-Num text was read in 1941.
Elsewhere Stinnett demonstrates why he thinks most of the 5-Num text messages were decoded & understood, and why Japan's supposedly airtight "radio silence" was anything but.