BLOCK CONTAINS CLAUSE:
Integer -1 of the BLOCK CONTAINS clause indicates the block size either in terms of records or in terms of characters. For illustration, BLOCK CONTAINS 50 RECORDS that means there are 50 records in the block.
RECORDS CONTAINS CLAUSE:
This clause indicates the records size. Integer-2 indicates the number of characters in a record. The RECORD CONTAINS clause is mainly used for documentary aims only.