Abbreviations in effects

For example, a string with an effect: Solid Pattern

static const char _data_FX_MODE_STATIC_PATTERN[] PROGMEM = "Solid Pattern@Fg size,Bg size;Fg,!;!;;pal=0";

What do abbreviations Fg, Bg, Fx means?
Fx, or fixed is it just a color?
Bg, or background is it a background color?
Fg - there is not even an assumption.

Fx: Effects
Bg: Background
Fg: Foreground

I think.

This is usually one of the colors used by the effect, but not the effect itself.

it seems to be true

file index.js

else if (i==0) btn.innerHTML = "Fx";
			else if (i==1) btn.innerHTML = "Bg";
			else btn.innerHTML = "Cs";

Whats mean Cs, custom?


Thank you very much!