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As an example of the usage of table handling facilities, the previous example selection specification can also be made as follows:
SEL/INP=0/OUT=A (OBJECT = N*4151 & DATE <= 3MAR89)
SEL/INP=0/OUT=B OBJECT = M81*
The UNION command combines the two selections A and B in one tabel 1. Similarly, the INTERSECTION function serves to obtain a table of entries which occur in each of two tables, and the DIFFERENCE command will produce a table of entries which appear in only one of two tables.
If, after the union operation, the tables A and B are no longer needed, it is a good idea to delete them with:
DELETE/INP=A , and: DELETE/INP=B
You will be prompted for confirmation of the deletion.