You can nest a declaration within a declaration.
STRUCTURE /SALE/ CHARACTER*32 BUYER INTEGER*2 QUANTITY STRUCTURE /PRODUCT/ ITEM INTEGER*4 ID CHARACTER*16 NAME CHARACTER*8 MODEL REAL*4 COST REAL*4 PRICE END STRUCTURE END STRUCTURE
Here, the structure SALE still contains the same three fields as in the prior example: BUYER, QUANTITY, and ITEM. The field ITEM is an example of a field-list (in this case, a single-element list), as defined under "Structure Declaration."
The size and complexity of the various structures determine which style of substructure declaration is best to use in a given situation.