BSAM arranges records sequentially in the order in which they are entered. A data set that has this organization is a sequential data set. The user organizes records with other records into blocks. This is basic access. You can use BSAM with the following data types:

• basic format sequential data sets (before z/OS 1.7 these were known as sequential data sets or more accurately as non-extended-format sequential data sets)
• large format sequential data sets
• extended-format data sets
• z/OS UNIX files