My suggestion: it's the "mode change" code/character found in various IBM punchcard encodings, punch 11-8-7, represented by an upper-case delta.
Rendering this slightly differently from the regular Greek letter, would make sense, I guess. This may also explain the varying representations in the manuals: some would represent this like in common EBCDIC charts, as a delta, while others would refer to it as represented in the actual on-screen character set.
(There is also the rather common problem with special characters in manuals, where the font used for the chart doesn't comprehend the particular glyph, giving rise to alternative, often more abstract representations, as these symbols were drawn in later.)
IBM Selectric Electric Typewriter left margin symbol indicator thingy on the little carriage position indicator plate between the keys and the platen of the typewriter. Most high schools had rows of these typewriters in a classroom to teach touch typing until at least the 90s when they were displaced by PC software. I don't think high schools teach typing anymore, would not work well on iPads.
I was there in the 80s, and I remember this character being used margin/tab displaying purposes in at least one word processor program. It seems an obvious use, IBM literally used that symbol for that purpose on their typewriters. Does anyone else remember the name of the word processor program?
It’s a caret indicator, also known as a ‘meter indicator’ or ‘meter movement’, used in navigation devices and on slide rules to indicate two states - a ‘value’ and a ‘register’, where the register state is indicated inside the box, and the value by whatever the arrow edge is pointing to. In a slide rule application, two independently movable bars are contained within the area of the symbol, with the pointer side used to select values on a scale, and the register ‘box’ side showing the results according to slide bar positioning.
It is also commonly used in compass devices to indicate a direction/bearing set by the user as a waypoint, and in digital navigation systems common at the time, would often be used in combination with the filled-in version to indicate course accuracy - when filled, the navigator is on-course, when emptied, a correction must be made.
There are also archaic physical versions of this symbol in the form of paper clips which can slide along the edge of a form, indicating the next step of a form for a department or staff member to be working on.
It was also used to indicate end of line positions in IBM typewriters, as mentioned by others in this thread.
Rendering this slightly differently from the regular Greek letter, would make sense, I guess. This may also explain the varying representations in the manuals: some would represent this like in common EBCDIC charts, as a delta, while others would refer to it as represented in the actual on-screen character set.
(There is also the rather common problem with special characters in manuals, where the font used for the chart doesn't comprehend the particular glyph, giving rise to alternative, often more abstract representations, as these symbols were drawn in later.)
I was there in the 80s, and I remember this character being used margin/tab displaying purposes in at least one word processor program. It seems an obvious use, IBM literally used that symbol for that purpose on their typewriters. Does anyone else remember the name of the word processor program?
Maybe you're thinking of DisplayWrite? See the second screenshot at https://www.dosdays.co.uk/topics/Software/ibm_displaywrite.p...
It is also commonly used in compass devices to indicate a direction/bearing set by the user as a waypoint, and in digital navigation systems common at the time, would often be used in combination with the filled-in version to indicate course accuracy - when filled, the navigator is on-course, when emptied, a correction must be made.
There are also archaic physical versions of this symbol in the form of paper clips which can slide along the edge of a form, indicating the next step of a form for a department or staff member to be working on.
It was also used to indicate end of line positions in IBM typewriters, as mentioned by others in this thread.
So, a general purpose cursor/caret indicator…