Software maintenance differs significantly from hardware maintenance, because software doesn't age (and aging is the primary cause of hardware malfunction). Software malfunction can arise, despite all the efforts to avoid and anticipate it, out of several reasons:

• faults within the software which where not discovered during system testing or during regular operation
• irregular operation by system operators,
• physical damage of the memory (storage) media.

Also, sometimes operators jump to conclusion that the fault is within the software, while it is somewhere else - in the environment, that is, outside the system, or in the hardware, or there is actually no fault at all, but it is a case of misunderstanding of the expected operation of the equipment. Such faults are not related to software of the system.

Fault removal

If it is established as a fact that there is a fault ("bug") in the software which causes the system not to work as its documentation, GVS will remove such faults on its own expense, for at least 10 years since beggining of system operation, and otherwise 10 years since the declaration of end of life of that version of software.

Problems arising from irregular operation by system operators - mostly wrong setting or programming of the system - are best solved by consultation with GVS technical staff, either through technical support, or by remote operation, if applicable. If that doesn't work, GVS expert may come and solve the problem on-site.

Other problems, not arising from irregular operation by system operators, but from an unknown source, are handled similarly. That is, there is a problem that the operators can't solve, although they have not made any changes to the system.

Data recovery

If we regard system data (database) as part of the system software, we have to consider the possibility of faults in the data. Data can be damaged or lost in several cases:

• damage by environmental influences like fire, mechanical impact and other,
• hardware malfunction,
• irregular operation by system operators.

In software controlled systems which GVS manufactures, there are several levels of data storage and defined procedures for data recovery. Unfortunately, there is a possibility that the damage is such that standard procedures can't solve the problem. In that case, special procedures for data recovery may be used (which are software version dependent). Even these special procedures will not recover data which is permanently lost, in all its copies. In these cases, data must be reconstructed, which is also a software maintenance procedure.

Minimal software changes

Software maintence covers minimal changes in the software, mostly of "cosmetical" nature. These are not software faults, but customer needs or whishes for small changes which will make the software easier for use or otherwise more adept to the way that the customer uses it. These kind of changes are not an obligation of GVS, but GVS will gladly meet most such requirements, if they contribute to the quality of the system as a whole, as the often do.