[Gnuplot-info] "set key noautotitle" ignored on explicit column name?

[Rhys U. <rhy...@gm...>]

Why does the first plot below obey "set key noautotitle" while the
second one ignores it?

$ gnuplot -V
gnuplot 4.6 patchlevel 5

$ file ~/.gnuplot  # No rcfile magic up my sleeve
/h2/rhys/.gnuplot: cannot open `/h2/rhys/.gnuplot' (No such file or directory)

$ cat data
x
1
2
3

$ gnuplot
gnuplot> set key noautotitle
gnuplot> plot 'data' using 0:1    # First
gnuplot> plot 'data' using 0:"x"  # Second

Why does this third plot autotitle "correctly" from the plot
specification while the fourth behaves as if I said "set key autotitle
columnheader"?

gnuplot> set key autotitle
gnuplot> plot 'data' using 0:1    # Third
gnuplot> plot 'data' using 0:"x"  # Fourth

I find the behaviors on the second and fourth plots to be buggy, but
perhaps I'm misunderstanding something implicit about using a named
column.

- Rhys