[amibroker] Modified Trailing stop

[pmxgs]

Hi all,

 I would like to implement a "modified trailing stop", that just 
trails one time, for example I define the trailing stop to trail by 
1%. Then, as soon as the price goes up by 1% the stop is raised to the 
entrypoint level (which is the usual way a trailing stop works), but 
from this moment on, the stop would stay at that point even if the 
price rose 10%. 
Can someone give an hint on how I can accomplish this?

thanks