Analysis of information sources in references of the Wikipedia article "Colon (punctuation)" in English language version.
Back in the typewriter day, when fading ink ribbons could result in commas being mistaken for periods and vice versa, typists were taught to insert 2 spaces after the period to differentiate between the two. The same happened with colons and semicolons: 2 spaces were left after a colon; 1 space after a semicolon.
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: CS1 maint: numeric names: authors list (link)In the medieval and early modern eras, [...] the colon and raised dot [...] signal a contracted word [...].
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: CS1 maint: numeric names: authors list (link)Back in the typewriter day, when fading ink ribbons could result in commas being mistaken for periods and vice versa, typists were taught to insert 2 spaces after the period to differentiate between the two. The same happened with colons and semicolons: 2 spaces were left after a colon; 1 space after a semicolon.
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