The OCCURS clause that is used to define tables can optionally have an INDEXED phrase. This phrase involves the names of data items which are to be used as subscripts to specify table elements. These data item is termed as index. The illustration below describes the table description with the INDEXED phrase.
The reference to an element of this table can be completed as YEAR (F1, D1, Y1) having set suitable values to the index names F1, D1 and Y1.
The common form of the INDEXED phrase is as shown below:
INDEXED BY index-name-1 [, index-name-2]...
The OCCURS clause with an INDEXED phrase takes the form as shown below: