The slotted page structure is used for organizing records in a block. The slotted page structure contains a header at the beginning of each block.

Variable length records arise in a system in several ways like, Storage of multiple record types in a file. Record types that allow variable lengths for one or more fields. Record types that allow repeating fields, such as arrays or multisets.

A null-bitmap indicates that the attributes of a particular record have null values.

The header in the slotted page structure does not contain the size of all the records put together in the header but it contains the number of record entries, the end of free space and an array containing location and size of each record.

A file header is a certain number of bytes allocated at the beginning of the file. It contains a variety of information about the file and it can be used to point the first record by storing the address of the first record in it.

It is tough to delete a record from the fixed length records but it is easier to delete a record from the variable length record. Thus, implementation of variable records is preferred.

As the addresses can be thought of as pointers, the deleted records thus form a linked list. The linked list formed by the deleted records is called as a free list.

Variable length records can be implemented in databases. There are different techniques to implement variable length records.

Jukeboxes are the devices that store a lot of optical disks and load them automatically on demand.