The purpose appears to be to set the 'title' property of the legend object to be 'Order'.
At least that what appears when I run this code:
xx = -1:0.1:1;
yy = xx.^2;
figure;
plot(xx,yy,'LineWidth',2);
axis([-1 1 -0.2 1.2] )
h = legend(['f*';'10';'Ch']);
v = get(h,'title'); % what is the purpose?
set(v,'string','Order'); % what is the purpose?
See the documentation section on Add Title to Legend (link) for details. Creating legend titles this way is relatively recent.
