Stocks software support custom indicators, similar to the following way,

VOLUME:=MA (VOL, N)/VOL.
MID:=100 * (HIGH + LOW - REF (HIGH and LOW, 1))/(HIGH and LOW);
EMV: MA (MID * VOLUME * (HIGH - LOW)/MA (HIGH - LOW, N), N);
MAEMV: MA (EMV, M);

This is how to achieve? Do every quotation software to realize their own a set of programming a scripting language?