True for graphics object handles
ishghandle(h) returns an array that contains 1's where the elements of h are handles to existing graphic objects and 0's where they are not. Differs from ishandle in that Simulink® objects handles return false.
Create a plot and find the valid handles:
x = [1:10]; y = [1:10]; p = plot(x,y); ishghandle(p)
ans = 1