Several of the codes are taken from The Telegraph Instructor by G.M. Dodge.2 Dodge notes:
Codes that are not listed in the 1901 edition of Dodge are marked with an asterisk (*).
In the above list, the numbers 19 and 31 refer to train order operations whereby messages from the dispatcher about changes in railroad routing and scheduling were written on paper forms. Form 19 was designed to be passed to the train as it went through a station at speed. Form 31 required hand delivery for confirmation.
Today, amateur radio operators still use codes 73 and 88 regularly, and -30- is used in journalism, as it was shorthand for "No more - the end". The Young Ladies Radio League uses code 33 to mean "love sealed with friendship and mutual respect between one YL [young lady] and another YL"3 or simply "hugs." A once-used but unofficial code 99 meant "go to hell." The other codes have mostly fallen into disuse.4
The following code was taken from 1873 telegraph rulebook of the Lakeshore and Tuscarawas Valley Railway Company of Cleveland, Ohio.5
"1859 Western Union "92 Code" & Wood's 1864 "Telegraphic Numerals" & Comparison of Alphabetic Telegraph Codes". Retrieved 2008-11-23. http://www.civilwarsignals.org/pages/tele/wurules1866/92code.html ↩
Dodge, G.M. (1901). The telegraph instructor. Valparaiso, Ind.: Not Given. p. 50. https://books.google.com/books?id=zrxLAAAAYAAJ&pg=PA50 ↩
"Women in amateur radio - Amateur-radio-wiki". www.amateur-radio-wiki.net. Retrieved 2016-08-01. http://www.amateur-radio-wiki.net/index.php?title=Women_in_amateur_radio ↩
"Telegraph Rules: Adopted October 1, 1873 By Lake shore and Tuscarawas valley railway company". 1873. https://books.google.com/books?id=958pAAAAYAAJ&q=%22Wait+a+minute%22+%22important+business%22+%22have+you+anything+for+me%3F%22&pg=PA12 ↩