[ferret_users] error bars

[nguyen@xxxxxxxxxx]

Hi ferreters
I'm ploting 2 variables using plot/vs as follow:
plot/vs var1,var2

I want to append error bars on both variables, i.e., on x and y axes.
I believe the option Go error_bars works only if one plot a single
variable like
plot var
go error_bars poly var error

but it doesn't work for my case.
does anyone know how to do this?
many thanks
Hanh