"The fact that the person who made the documents used this notation casts doubt on their authenticity since typing it out numerically with a superscript ordinal suffix was quite difficult to do on an Selectric model typewriter which required a very involved process in which the user would have to feed the paper up half a line, manually remove the device's "font ball" which was used to place characters onto the paper, replace it with a ball with a smaller-sized font, advance the page back down half a line, and then put back the original font ball."
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Oh yes. And this was a technique taught to every admin clerk in those days, quite common.
NOT!
I learned to type in 1964. The goal for a typist was speed and accuracy. The idea that a typist would waste time on maneuvering a superscript "th" into a document is ludicrous, when a normal-type "th" was the accepted format.
In fact, the superscript "th" bothers me to this day, and what was wrong with rotary dial phones anyway?