Please purchase £500 Preference (stating which stock)
Stock in the Great Blankshire Railway, at a price not
exceeding £150 per cent., in my name, and send me the
account for the same, when I will forward my cheque for the
cost.
Yours faithfully
JANE SMITH.

The same form can of course be adapted for selling out, by substituting "sell" for "purchase," writing "less" for "not exceeding," and omitting the line as to forwarding the cheque.