RE: display.texi: (<line>,<col>) isn't documented.

[Drew Adams]

> But let's see when we disambiguate it a bit with a 'c' or a dash:
>
> 300c40  300:40  300-40
> 12c12   12:12   12-12
> 13c71   13:71   13-71
> 1c0     1:0     1-0
> 12345c0 12345:0 12345-0
> 12345c12345     12345:12345     12345-12345
>
> With c the meaning is clearer, I think, with the dash it's more
> readable.  I'd choose the single c.

In 30c40, what makes one necessarily associate the c with 40 and not 30? In
France, one writes 11h25 for 11:25 a.m. (time). That is, the `h' is
associated with the first number. Units are most often written after
quantities, not before: 12m, 15'34", 15min 34sec. (The US dollar is one
exception ($12); there are others.)

Some people have said that it is obvious that line comes before column. I
don't see why that's obvious, but if most people think it is, then there is
nothing wrong with (12,25).

12:25 can be confused with a time. 12-25 can be confused with a range of
some kind (12 through 25). 12.25 can be confused with a decimal number.
Parens are needed for grouping in 12,25 and 12;25 - otherwise, they can be
confused with separate mode-line entries (meaning whatever). 12'25" can be
confused with several things (but it does have the advantage of suggesting
major/primary (line) and minor/secondary (column) units - assuming that it
is clear to all that line is primary).

I think explicit units help, and are consistent and clear also when only one
unit is used (25c). I think they should be placed after the numbers, not
before: 12<line-unit>25<column-unit>. So, 12L25C or 12l25c or 12y25x or some
such. If we can spare a space, then it is even more readable: 12L 25C.

Uppercase letters such as L and C are hard to separate visually from the
digits. Using l and c risks confusion between l and 1.

It's true that x and y suggest geometric position, not lines and columns. x
and y also suggest horizontal and vertical directions, but they do not
suggest lines and columns. In a buffer, horizontal and vertical positions
can only mean lines and columns, however (unless one is thinking pixels).
It's true that y suggests increasing values toward the top, but practice
would soon put the lie to that association.

I prefer 25x 12y (or 12y 25x), personally, but I can live with any of the
proposals, including what we have now. Let the Grand Gnu choose.