Use of [], rather than ()

I don’t think square brackets were even invented until the early 1970s, when they started showing up on computer keyboards. Before that, we had to use the plain old parentheses found on typewriters.

Wild Guess: Computer languages were the first applications for the use of these square brackets. The field of mathematics also had specific uses for square brackets, as discussed in this thread, but usually required many other tricky typesetting techniques.

In normal human-language text, we should always follow our style manual (if your boss or company doesn’t have a style manual, then play it safe, and use parentheses only). Remember, that a lot of text is still typed on old typewriters, (or typeset on old equipment). Therefore, most style manuals do not automatically assume that square and curly brackets are available.


You know, it really does look weird now that someone has written it out. I told my students to ignore that part of the textbook and just do the ellipsis without brackets, just as we did “back in the day.”

Honestly, I think those folks at the MLA need to leave well enough alone.

You will find them in many textbooks long before then.

As for keyboards - they appeared in the ASCII 1963 specification.

(source - http://www.wps.com/projects/codes/index.html Their mention of one square brace being added in 1967 seems to be in error, as they are present in the 1963 spec, and, IIRC, are part of the COBOL graphics that 1963 intended to support)

When I graduated from high school I was given a portable typewriter. One of its features was that 4 of the keys had removable typefaces that could be replaced with a variety of special character sets obtainable from the manufacturer. I think the “math” set I had may have included square braces.

Most books on computer language or books on human metalanguage will start off with a set of definitions on use of () {} and other groupings. They vary a lot from one author to another, as a student will quickly find out and complain about.