The quality of being unchanging.
The content of a document is fixed in that it is stable and resists change, but it may not be immutable. Words may be erased or added. 'Immutability' connotes a significantly greater resistance to change, such that any change is clearly evident. In information technology, immutability is accomplished by creating a process to demonstrate that the record has not been altered.
OCLC/RLG 2001, p. 4 Digital objects are not immutable therefore, the change history of the object must be maintained over time to ensure its authenticity and integrity.