Why the gd based terminal does support character entity reference ?

[Tatsuro M. <tma...@ya...>]

Hello

I made a feature request:

Supports character entity reference

https://sourceforge.net/p/gnuplot/feature-requests/440/

As I wrote there, on the gd based terminals, one can use 

for example following code to write a Greek symbol "theta".

set term png
set output 'test.png'
plot sin(x) title '{/:Italic \θ}'
set output

Why this feature only supports on the gd based terminals?

Does anyone know reasons?

Tatsurp