Mục đích ra lệnh cung cấp khả năng cơ bản Thiết lập yêu cầu thực hiện hoặc hạn chế Thiết lập yêu cầu thực hiện hoặc hạn chế sử dụng trong báo cáo chi tiết kỹ thuật được viết trong giọng nói thụ động sử dụng bao gồm tài liệu tham khảo, tiêu chuẩn hoặc tài liệu khác như là một bổ sung cho các yêu cầu | 188 4 SOFTWARE REQUIREMENTS ENGINEERING Table Imperatives found in requirements specifications and their purpose Wilson97 Imperative Purpose Shall Must Must not Is required to Are applicable Dictates provision of fundamental capability Establishes performance requirements or constraints Establishes performance requirements or constraints Used in specifications statements written in passive voice Used to include by reference standards or other documentation as an addition to the requirements being specified Responsible for Used as an imperative for systems whose architectures are already defined Will Generally used to cite things that the operational or development environment are to provide to the capability being specified Should Not recommended for use Weak phrases Imperatives Imperatives are given in Table . Continuances follow an imperative and introduce the specification of requirements at a lower level. Continuances include Below As follows Following Listed In particular Support Directives are words and phrases that point to illustrative information Figure Table For example Options give the developer latitude in satisfying the specifications and include Can May Optionally Weak phrases which should be avoided in SRS include Adequate As a minimum REQUIREMENTS VALIDATION AND REVIEW 189 As applicable Be able to Be capable But not limited to Capability of Capability to Effective If practical Normal Provide for Timely TBD These fine-grained measures can minimally be used to measure certain size qualities of the SRS such as Lines of text Imperatives Subjects unique words following imperatives Paragraphs Certain ratios can also be computed from these fine-grained measures which can be used to judge the fitness of the specification of these ratios are shown in Table Readability statistics similar to those used to measure writing level can be used as a quality measure for SRS. Readability statistics include Flesch Reading Ease Index Number of syllables .
