The figures showing through the bottom aperture are used to indicate the page. With the key showing in the picture below, page one is indicated by 3, page two by 8 and so on. This figure will be the first one in a code group. In the aperture to the right, ranges of 2-figure groups show, and the idea is, you can choose any 2-figure group in the provided range to indicate the row. These figures will occupy places two and three in the finished code group. Finally, the figures in the top aperture are used to indicate the column in which the plaintext element to encode stands.
To encode 2 T-34 tanks, we first locate the figure "2" on page one, second row, second column. The code group can be one of the following: 3683, 3693, 3703, 3713, 3723, 3733, 3743, or 3753. On page two, we find a list of different tank-types, and "T-34" sits on the last row, column eight. Let's encode it as 8924. The word "tank", which really is unnecessary, is found on page three (not shown here), and it could be rendered 1377, so the final cryptogram could read: 3723 8924 1377.
