AbstractiStar is a goal-based requirements modelling language, being used in both industrial and academic projects of different domains. Often the language is extended to incorporate new constructs related to a particular application domain or to adjust it to practical situations during requirements modelling. Currently, the language is undergoing standardisation, and several studies have focused on the analysis of iStar variations to identify similarities and to define a core. This does not imply or constrain the need for iStar to continue to be extended. This paper contributes to the understanding of how iStar is extended by analysing how iStar researchers perform iStar extensions. To address this question, we followed a qualitative approach based on interviews involving 20 researchers from different research groups that proposed iStar extensions. The analysis revealed a good understanding about what extending a modelling language means and pointed out differences about how extensions are proposed. We discovered categories that impact positively on iStar extensions (such as reusing existing extensions, proposing extensions in abstract and concrete syntaxes, and creating new modelling tools), and other categories that impact negatively (such as modifying representations of the original constructs, proposing extensions in an ad hoc fashion and not carefully choosing graphical representations). We also evaluated the findings of interviews through an online survey answered by 30 iStar researchers. Finally, we proposed a set of guidelines to support the proposal for better future iStar extensions.

中文翻译：

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了解 iStar 扩展提案中的重要内容：研究人员的观点

AbstractiStar 是一种基于目标的需求建模语言，用于不同领域的工业和学术项目。通常，语言会被扩展以合并与特定应用程序领域相关的新结构，或者在需求建模期间将其调整到实际情况。目前，该语言正在进行标准化，一些研究集中在分析 iStar 变体以识别相似性并定义核心。这并不意味着或限制 iStar 需要继续扩展。本文通过分析 iStar 研究人员如何进行 iStar 扩展，有助于理解 iStar 是如何扩展的。为了回答这个问题，我们采用了基于对来自不同研究小组的 20 名研究人员进行访谈的定性方法，这些研究人员提出了 iStar 扩展。该分析揭示了对扩展建模语言意味着什么的良好理解，并指出了关于如何提出扩展的差异。我们发现了对 iStar 扩展产生积极影响的类别（例如重用现有扩展，提出抽象和具体语法的扩展，以及创建新的建模工具），以及其他负面影响的类别（例如修改原始结构的表示，在一种特别的时尚，而不是仔细选择图形表示）。我们还通过由 30 位 iStar 研究人员回答的在线调查评估了访谈结果。最后，