The diary has three kinds of coded entries:
(1) Slash marks (/), heavy dots (.), x marks (x), and plus marks (+), all appearing in the right margin, except for the plus signs, which appear in the left margin under the entry date
(2) Marks in the right margin that sometimes include marks like dot-dash code and others not similar to them
(3) Marks in the entries in a code of dots (.) and dashes (_) like the Morse telegraphic code, though not identical with its current form.
(1) The slash marks (/) in the right margins occurred from the early days of the Diary after the marriage of William and Regina Roos until they were suddenly replaced by heavy dots (.) on Sept. 4, 1861. These were used throughout the time of William’s marriage to Regina (1861–1876). After marrying Elizabeth Ranft in 1880, William began to use the symbol x (x) which quickly transformed into plus marks (+), which were placed most frequently in the left margin under the date of the entry.
A number of reasons support the belief that all three types of marks recorded sexual activity between William and his two wives, i. e., one / = one occurrence of sexual activity. The marks’ occasional appearance next to “L. P.” (presumed to mean “lambskin or linen prophylactic”) furthers this argument. During William’s marriages to Regina and Elizabeth, these marks are recorded in relation to the beginning and end of his wives’ menstrual cycles which he recorded in dot-dash code. As a newlywed, William seems to have tallied the number of times sexual activity took place; for example, the number 6 in the heading of the second page of the diary, and the number 237 in the heading of the page beginning Sept. 20, 1861.
(2) The second type of mark occurs almost entirely in 1868–1870, always in the margin, and is not understood. Some combine letter equivalents from the dot-dash code with other symbols, such as dots, hyphens, dashes, in some cases letters, which are seldom understandable.
(3) Beginning on March 17, 1862, William used a dot-dash code apparently derived from a version of the Morse telegraphic code. A volunteer researcher discovered this version of Morse code was in use in the 1840s. William may have used the code to keep others from knowing his meaning, and most of the references are to bodily functions, about which he may have had some shyness. The coded words can be deciphered by a sheet that was loose in the diary, according to Henry Ziegler Steinway, which gave the code and its meaning in what is presumed to be William’s hand. The code and its equivalents are as follows:
A ._ B _... C .. . D _.. E . F ._. G _ _. H . ... I .. J _._. K _._ L ___ M _ _ N _.
O .. P ..... Q .._. R . .. S ... T _ U .._ V ..._ W . _ _ X ._.. Y .. .. Z ... .
The letters I and O are represented by the same symbol. Usually the word context indicates which is correct, but not always. Individual annotations decipher dot-dash coded words in CAPITAL LETTERS.