Use (x) when (x) is part of a command, for example:

x="an_alias"
use (x)

use &x when x is itself a command, or an evaluable expression, for example:

x="select * from an_alias"
&x

runs the select statement, while (x) do nothing

FRanco

>Are there any guidelines as when we can use (X) and when we need to use &X ? I know that (X) is faster, but it dooes not always work?