Doug Ewell wrote:
And indeed, the forthcoming Unicode Technical Note we are going to be
writing to supplement the introduction of the characters in L2/19-025,
whether next year or later, will recommend ISO 6429 sequences like this
to implement features like background and foreground colors, inverse
video, and more, which are not available as plain-text characters.
Back in the late 1980s I had the opportunity for some time, from time to
time, to use a colour terminal that was attached to a mainframe computer
as if it were just another basic terminal attached to a mainframe. So it
could be used just as a basic terminal attached to a mainframe, and it
was often used in that manner.
Yet it also responded to Escape sequences which enabled it to do colour
graphics, with, as best I remember now, commands to choose a colour and
draw lines and so on.
I note with interest Doug's suggestion to use Escape routines.
However, these days systems tend to be more complicated at the
underlying platform level and there is often communication between
systems and so on and I wonder whether using Escape codes as such might
be prone to strange problems in some circumstances before getting to the
emulator software. With various platforms in common use I am wondering
whether there might be problems in some cases. Maybe there is no issue
and everything would be fine, yet I opine that that possibility of
problems need to be looked at.
I wonder if a new character, say U+FFF6, in the Specials section, could
be defined that could be regarded as just an ordinary printing character
in many circumstances yet as having exactly the same meaning as the
Escape character in some circumstances, such as in an emulator.
If that were done then the desired result could be achieved in a
carefully structured manner rather than risk clashes over effectively
sometimes trying to use the Escape character in two ways at the same
time, perhaps with one of the ways being deep in the operating system
and one in the terminal emulator with the way deep in the operating
system usually winning.
William Overington
Tuesday 22 January 2019
