Application programs use Record type and Record Occurrence to access data in IDMS.
Record Type :
A Record type is the structural component that conveys the format in which records are stored in the database. Record type is a group of similar record occurrences that exists in the database.
Record Occurrence :
A Record occurrence is the actual content of data that is stored in the database. Record occurrence is the basic addressable unit of data under IDMS database. Record occurrences are always associated to a specific Record type. Each record occurrence can be of fixed or variable length. A record occurrence is further subdivided into fields or data elements based on its structure.
Record occurrence has two components, Prefix and Data
The Prefix consists of pointers. These pointers point to the NEXT, PRIOR and OWNER records. Each pointer is in form of a DBKEY. The pointer refers to physical location of
another record occurrence that is related it.
The Data is the set of bytes that represents the record value, which may have some internal structure defined by the application developer.