Topic summary
Entry-sequenced data set
Extracted from the Wikipedia article Virtual Storage Access Method.
Sequential organization
An entry-sequenced data set (ESDS) is a type of data set organization supported by VSAM. Records are accessed based on their sequential order, that is, the order in which they were written to the file; which means that accessing a particular record involves searching all the records sequentially until it is located, or by using a Relative byte address (RBA), i.e., the number of bytes from the beginning of the file to start reading.