当前的服务接口和行为被作为一个版本保留，同时更新的服务被作为另一个版本而引入。
The current service interface and behavior is preserved as one version, while the newer service is introduced as another version.
要有效地使用该能力监视系统状态、电子邮件和任何其他需要的参数，我们需要保留这种可变性，同时为其使用提供一个简单的接口。
To use the capability effectively for monitoring system status, E-mail messages, and any other desired parameter, we need to preserve this variability while providing a simple interface for its usage.
在Ada 2005中，引入了一个新的保留词接口来解决单次继承性的限制问题。
In Ada 2005 a new reserved word interface was introduced to resolve the limitations of single inheritance.
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