1、维护任务估算
Project estimation often doesn’t include the maintenance effort during the lifetime of an application system. But it usually exceeds the other application development costs. Software maintenance is often defined as the modification of a software product after delivery to correct faults, to improve performance or other attributes, or to adapt the product to a changed environment. Practical experience shows that IT systems do live longer than expected. It’s a common practice that the costs for maintenance are cumulated during the lifetime of a system without controlling the amount and without differentiating between the different kinds of costs. Like in a supermarket the user is afterwards astonished that the many cheap goods in the basket (comparably maintenance requirements) cumulate to a large sum at the cash point. It’s only a pity that in software maintenance nothing can be removed from the basket afterwards (to stick to the analogy with the supermarket).
项目估算通常不会考虑在应用系统生命周期内的维护任务的估算问题。但是对软件进行维护的费用往往又会超过其他应用开发的费用。软件维护通常定义为在提交之后对软件所做的修改，比如纠正错误，提高软件性能或者其他属性，以及根据改变后的环境对产品进行升级等。实际经验表明，IT系统的生命周期通常比预料的要长。常用的做法是将维护所需的费用计算在系统生命周期之内，而对费用的总量不加以控制，并且也不区分各种费用之间的区别。结果往往是如同一个在超级市场购物的顾客结账时惊讶地发现，购物篮（我们可以将其比作软件维护的需求）中一些本来很便宜的货物算在一起居然是一个很大的数目。但遗憾的是，软件维护中的任何需求又都不能从“购物篮”中丢出去（如同在超市购物时不能够舍弃某些生活必需品一样）。
It should always be kept in mind that the IFPUG (International Function Point User Group) definition holds that maintenance tasks do not change the functionality of an application system. If it does so it will be an enhancement instead.
需要强调的是，IFPUG（International Function Point User Group，国际功能点用户群组）定义认为，软件维护并不会改变一个应用系统的功能。如果维护中改变了系统的功能，则该应用系统就应该被一个升级版本所代替。
The UKSMA and NESMA Standard
Besides the ISO 14764 standard ?Software Engineering – Software Maintenance“ the UKSMA (United Kingdom Software Metrics Association) published together with the ISBSG (International Software Benchmarking Standards Group) in Juli 2001 in the series of the UKSMA Quality Measurement Standards the standard ?Measuring Software Maintenance and Support“, Version 0.5 Draft [UKS], available from the Internet: http://www.uksma.co.uk . This standard distinguishes between maintenance, support and operations (see table 1).
Project estimation often doesn’t include the maintenance effort during the lifetime of an application system. But it usually exceeds the other application development costs. Software maintenance is often defined as the modification of a software product after delivery to correct faults, to improve performance or other attributes, or to adapt the product to a changed environment. Practical experience shows that IT systems do live longer than expected. It’s a common practice that the costs for maintenance are cumulated during the lifetime of a system without controlling the amount and without differentiating between the different kinds of costs. Like in a supermarket the user is afterwards astonished that the many cheap goods in the basket (comparably maintenance requirements) cumulate to a large sum at the cash point. It’s only a pity that in software maintenance nothing can be removed from the basket afterwards (to stick to the analogy with the supermarket).
项目估算通常不会考虑在应用系统生命周期内的维护任务的估算问题。但是对软件进行维护的费用往往又会超过其他应用开发的费用。软件维护通常定义为在提交之后对软件所做的修改，比如纠正错误，提高软件性能或者其他属性，以及根据改变后的环境对产品进行升级等。实际经验表明，IT系统的生命周期通常比预料的要长。常用的做法是将维护所需的费用计算在系统生命周期之内，而对费用的总量不加以控制，并且也不区分各种费用之间的区别。结果往往是如同一个在超级市场购物的顾客结账时惊讶地发现，购物篮（我们可以将其比作软件维护的需求）中一些本来很便宜的货物算在一起居然是一个很大的数目。但遗憾的是，软件维护中的任何需求又都不能从“购物篮”中丢出去（如同在超市购物时不能够舍弃某些生活必需品一样）。
It should always be kept in mind that the IFPUG (International Function Point User Group) definition holds that maintenance tasks do not change the functionality of an application system. If it does so it will be an enhancement instead.
需要强调的是，IFPUG（International Function Point User Group，国际功能点用户群组）定义认为，软件维护并不会改变一个应用系统的功能。如果维护中改变了系统的功能，则该应用系统就应该被一个升级版本所代替。
The UKSMA and NESMA Standard
Besides the ISO 14764 standard ?Software Engineering – Software Maintenance“ the UKSMA (United Kingdom Software Metrics Association) published together with the ISBSG (International Software Benchmarking Standards Group) in Juli 2001 in the series of the UKSMA Quality Measurement Standards the standard ?Measuring Software Maintenance and Support“, Version 0.5 Draft [UKS], available from the Internet: http://www.uksma.co.uk . This standard distinguishes between maintenance, support and operations (see table 1).
Development (1)通告:http://www.qqread.com/erp/34/y923143004.html  更多内容请看计算机维护、硬盘维护与数据恢复专区、系统维护手册专题，或进入讨论组讨论。
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