In the Virtual Storage Access Method (VSAM), a collection of alternate-index entries used to sequence and locate one or more data records in a base cluster. Each alternate-index record contains an alternate-key value and one or more pointers. When the alternate index supports a key-sequenced data set (KSDS), the pointer is the prime key value of each data record. When the alternate index supports an entry-sequenced data set (ESDS), the pointer is the relative byte address (RBA) value of the data records. See also key, alternate-index entry, alternate key.