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Maintenance of software products

Source ISO 9000-3: 1991, 5.10.

Maintenance activities for software products are typically classified into the following:

problem resolution;
interface modification;
functional expansion or performance improvement.


All changes to the software (for reasons of problem resolution, interface modifications, functional expansion or performance improvement) carried out during maintenance should be made in accordance with the same procedures, as far as possible, used for the development of the software product. All such changes should also be documented in accordance with the procedures for document control and configuration management.

a) Problem resolution:
Problem resolution involves the detection, analysis and correction of software nonconformities causing operational problems. When resolving problems, temporary fixes may be used to minimize downtime and permanent modifications carried out later.
b) Interface modifications:
Interface modifications may be required when additions or changes are made to the hardware system, or components, controlled by the software.
c) Functional expansion or performance improvement:
Functional expansion or performance improvement of existing functions may be required by the purchaser in the maintenance stage.


The items to be maintained, and the period of time for which they should be maintained, should be specified in the contract. The following are examples of such items:

data and their structures;
documents for purchaser and/or user;
documents for supplier's use.