Software today is a ubiquitous and essential tool in the modern measurement and testing laboratory. It has been remarked by more than one developer that '... software would be fine if it were not for the user'. This of course is said tongue in cheek but it does highlight an important class of problems associated with software viz. the difficulties that can arise when the user is able to modify the way in which a program operates. User customisation of software is an area of increasing concern in laboratories seeking to acquire and/or maintain accreditation to internationally recognised quality standards such as ISO 17025 (formerly ISO Guide 25) or GLP/GMP.
This Guide examines, in general terms, the ways in which software may be modified by an end user, considers some of the pitfalls that may arise and discusses best practice for maintaining software in a state acceptable to accreditation agencies.