Step 1: Microfiche of Unit-Year Cards
From Donna Noelken, Archives Specialist: "This series is arranged by period: WWI 1912-1939, WWII 1940-1943, and by year beginning in August 1943- 1959. Index cards are arranged by unit type/arm of service and then by its numerical designation. The cards are further subdivided by divisions, brigades, groups, regiments, battalions, companies, squadrons, detachments etc. Units not found in a specific category may be found under miscellaneous or all others."

The microfiche cards are in the reading room in a rack or in drawers. These are organized by unit number, at the battalion level. So if you are looking for 29th Combat Engineer Battalion, you would find the fiche with the 29's. You read this on the microfiche reader (and I took pictures of the reader screen, so that I captured this information, to be able to check things when I was back home). The microfiche contain images of old IBM punch cards, one card for each year of the unit's MR's. There are 5-digit column groups across the card for each month of the year.

Here is the image (made before I perfected getting sharp hi-res images from reader screens) of the 1945 card for the 23rd Armored Infantry Battalion:

The unit number 0023 is at top left, followed by the type of unit. Below that are the 12 5-digit columns for the months. I wanted the April 1945 MRs for 23 AIB. So I noted that the number there was 01343. (Sometimes a unit's MRs will be split across microfilm reels, in which case there may be one or two numbers typed below the main number for the month. Be sure to note all of these and request all reels when submitting your pull slip.

Step 2: Pull Slip
You then fill out a pull slip with the information about the roll of microfilm you want.

From Donna Noelken, Archives Specialist: "Researchers may submit 3 pull slips with 3 item numbers per pull time (9 item numbers total). Pull times are every hour on the half-hour beginning at 8:30 a.m. and ending at 2:30 p.m. These are general instructions but enough to get a researcher started. Film pull request slips (Form 14001) must include: Type of unit records (morning reports, rosters, sick reports etc.), Name of unit, Month & year, and Item or box number."

Here is the pull slip that I submitted for the April 1945 microfilm roll that includes 23 AIB (take pictures of everything along the research process:

I can see that the handwriting for the box number appears to have been added and was not on my original pull slip. I think it was probably added by the staff who had to find the microfilm roll.

Step 3: Microfilm
Here are pictures of the box of microfilm that I received in 2011 in response to the pull slip above (take pictures of everything along the research process). Note that the box number is 72 and not the 172 written on the pull slip.

The box has a range of these 5-digit numbers (the leading zero is omitted). So this box has all the units that were assigned number 01331 to 01367 -- and not just 23 AIB's 01343.

Here is the large side of the box:

They have set up black blocks of images (a "flash") with at three points in the roll, so that if you want to find a specific group, you can use the fast forward on the reader until one of these blocks of black comes up. In this case, my 01343 is just before flash 2, so that I can advance to that flash spot and then back up through all the companies of 23 AIB to find the start of 01343 which is 23 AIB Bn HQ for April 1945.