There isn't a direct representation of AND or OR. However, this can be achieved in different ways. For example,
To use an OR
To see if a postage type is first class or expedited you can use the following
#Expedited#first class#[?][%Shipping method%][1STClass][2NDClass]
This looks for the shipping method within another string, where the other string contains all the values that the Shipping Method can be. If available 1StClass is used and if it is not one of the defined values 2NDClass is used.
To use an AND
To see if the Shipping Method is Expedited OR first class AND they have spent more than £100 you can use the following:
#Expedited#first class#[?][%Shipping method%][[%Grand total%][>]100[Recorded][1STClass]][2NDClass]
As in the OR example, this looks for 2 different shipping methods (the OR). It then looks at Grand Total and if this is more than 100 it uses Recorded otherwise 1St Class is used.
To include another level of AND you can replace the Recorded with another test condition (within the [ and ]).
More details and examples at: