A sign/abbreviation for "magister"

[James Kass via Unicode]

Ken Whistler replied,

 >> could be typed on old-style mechanical
 >> typewriters.  Quintessential plain-text, that.
 >
 > Nope. Typewriters were regularly used for
 > underscoring and for strikethrough, both of which
 > are *styling* of text, and not plain text. The
 > mere fact that some visual aspect of graphic
 > representation on a page of paper can be
 > implemented via a mechanical typewriter does not,
 > ipso facto, mean that particular feature is plain
 > text. The fact that I could also implement
 > superscripting and subscripting on a mechanical
 > typewriter via turning the platen up and down half
 > a line, also does not make *those* aspects of text
 > styling plain text. either.

Sorry if we disagree.

I've never used a typewriter for producing anything other than text.  
Just plain old unadorned text.  Plain text.  Colloquially speaking 
rather than speaking technically.  Text existed before the computer age.

A typewriter puts text on paper.  Pressing the "M" key while holding the 
"Shift" key puts "M" on the sheet.  Rolling the platen appropriately and 
striking "r" puts a superscript "r" on the sheet. Hitting the backspace 
key, rolling the platen a bit in the other direction and typing the 
"equals" key finishes this abbreviation in the text on the page.  Then 
the user rolls the platen to its earlier position and resumes typing.  
(It's way easier to do than to describe.)

If the typist didn't intend to put a superscript "r" on that page with a 
double underline, the typist wouldn't have bothered with all that jive.

It's about the importance one places on respecting authorial intent.

Anything reasonable done on a mechanical typewriter can be replicated in 
an electronic data display.  If necessary I'd use a kludge before I'd 
hold my breath waiting for direct encoding when the desired result is 
for the displayed text on the screen to match the handwritten text in 
the source as closely as possible.  (I've used lots of kludges while 
awaiting the real M=ͨCoy.)

Sure, underscoring was used for s̲t̲r̲e̲s̲s̲, but it wasn't used *as* a 
stylistic difference as much as it was used *in lieu* of the ability to 
make a stylistic difference, such as bolding or italicizing.  It's the 
"plain text" convention of that time, predating the asterisks or slashes 
used in the modern convention. Underscoring might be stripped without 
messing with the legibility, but so could tatweels and lots of other 
stuff.  If nothing should mung the asterisks and slashes used in the 
modern convention, then the earlier convention's underscoring is every 
bit as worthy of being preserved.  (If I'm not mistaken, there was also 
some kind of underscoring convention for titles which was used instead 
of placing titles in quotes.)

Strikethrough isn't stylistic if it's done to type a character which 
isn't present on one of the keys.  For example, letters with strokes 
used for minority languages, like "Ŧ".  I don't see strikethrough as 
"style" if the typist didn't want to waste White Out on a draft, either.

Perhaps I should have referred to typewritten text as seminal plain text 
rather than quintessential plain text, but quintessential scans better.

Speaking of text, computer age or otherwise, the O.E.D. definition of 
text as related to computers appears outdated and/or incomplete:
https://en.oxforddictionaries.com/definition/text
(definition 1.3)