Trailing stop formula

[Philip <pschmi02@xxxxxxxxxxx>]

Greetings,

I would like to ask your help in writing a formula for trailing stops. The
concepts themselves are very basic:

For short trades: H + ATR(10)
For long trades: L- ATR(10) . . . or some such, doesn't really matter at this
point.

But I'd like to write the formula in such a way that once a trade has been
entered, the stop ONLY moves in the direction of the trade, or stays at the
same level. Thus, in a short trade, the stop would only follow the market
down or stay unchanged, it would never retrace any progress it's made, never
give up any ground, even if the market moved up against the position. The
same would hold true for a long trade, in reverse naturally. The trailing
stop moves up with price, but goes sideways if the market drops, thereby
letting the stop take me out.

Has anyone been over this terrain? I am running MS 6.52.

Best regards,
Philip