Dict -> Dict -> List -> List data structure help.

[Wayne R]

 I am trying to create a complex data structure and I can't seem to
figure out how to arrange the dict and list constructs.  Here's the
basic scheme.  

 Dictionary ->    Dictionary            -> List                   ->
List
 (Store #)        (Transaction #)      (Line # of transaction)
(Details of transaction line)
 (usually 1,2,3)  (six digit A-X,1-9)  (1-999)                   (Sku
number, description, extended price) 

 Any ideas greatly welcomed.

Wayne