Editing Typewriter (section)

===== Three-bank typewriters =====
Certain models further reduced the number of keys and typebars by making each key perform three functions—each typebar could type three different characters. These little three-row machines were portable and could be used by journalists.<ref>{{Cite journal |last=Mosher |first=Charles Philo |date=10 April 1917 |title=Type-Writing Machine |url=https://books.google.com/books?id=DngbAQAAMAAJ&pg=PA537 |journal=Official Gazette of the United States Patent Office |page=537}}</ref>

Such three-row machines were popular with WWI journalists because they were lighter and more compact than four-bank typewriters, while they could type just as fast and use just as many symbols.<ref>Alan Seaver. [http://sevenels.net/typewriters/3banks.htm "Three-Bank Typewriters"]</ref> To include those symbols, three-row machines like the Bar-Let<ref>[https://www.typewriters101.com/collection.html "My Typewriter Collection: Bar-Let Model 2"].</ref> and the [[Smith Corona#Corona Typewriter Company|Corona]] No. 3 Typewriter<ref>Smithsonian National Museum of American History.
[https://www.si.edu/object/corona-typewriter%3Anmah_849921 "Corona No. 3 Typewriter"]</ref><ref>[https://www.typewriters101.com/store/p430/1921_Corona_Folding_No._3.html "1921 Corona Folding No. 3"].</ref> had two distinct shift keys performing different functions, a "CAP" shift (for uppercase) and a "FIG" shift (for numbers and symbols).<ref>Anthony Casillo. [https://books.google.com/books?id=emcqDwAAQBAJ ''Typewriters: Iconic Machines from the Golden Age of Mechanical Writing''].
2017. pp. 116; 197–198.</ref> They were thus also known as ''double-shift typewriters''.

[[Teletypewriter]]s also often used a three-row typewriter keyboard,<ref>[https://books.google.com/books?id=AuIOu97MduQC "Principles of Telegraphy, Teletypewriter"]. 1967. p. A-15.
"[Murray] used a 5-unit code with two shifts, [and] 
(...) use of a three-row typewriter-style keyboard, with the numerals assigned to the top row of keys. 
Therefore, the numeral 1 had to use the same combination as the letter Q, 2 the same combination as W, etc."</ref>
which looked superficially similar in that it also had two shift keys, "FIGS" (figures) and "LTRS" (letters). However, these [[Murray code]]-based machines generally did not allow each key to perform three functions and were a different technology from double-shift typewriters.{{efn|Unlike shift keys on double-shift typewriters, teletypewriter shift keys were stateful—like [[Shift Lock]]. Typing or transmitting FIGS once shifted all following characters to "figure shift", until LTRS shifted the code back to "letter shift". Hence those two shift keys did not allow teletypewriters to include lower- as well as upper-case characters. A further feature finally allowing that only arrived as a 1988 extension to the Murray-based [[Alphabet 2]] code,<ref>[http://archive.org/details/enf-ascii "The Evolution of Character Codes, 1874-1968"]. 2000. p. 8.</ref> close to that technology's obsolescence.}}