9.4.3.1 Features（特征）

Each Feature is associated with a Classifier called its featuringClassifier. The Feature represents some structural or behavioral characteristic for its featuringClassifier, except for Properties acting as qualifiers (see 9.5.3).

每個特征都和一個叫做特征化類目的類目相關(guān)聯(lián)。特征表現(xiàn)類目的某些結(jié)構(gòu)方面的或者是行為方面的特性。作為限定子的屬性除外。

The isStatic property specifies whether the characteristic relates to the Classifier’s instances considered individually (isStatic=false), or to the Classifier itself (isStatic=true). All semantics relating to Features that do not explicitly state whether the feature is static shall be assumed to refer to non-static Features. Where semantics are not explicitly specified for static Features, those semantics are undefined.

isStatic屬性定義特性是和類目的獨(dú)立的實(shí)例相有關(guān)（isStatic=false)，還是和類目本身有關(guān)。所有和沒有明確說明是否為靜態(tài)的特征有關(guān)的語義都應(yīng)該認(rèn)為涉及的是非靜態(tài)特征。當(dāng)語義沒有明確地為靜態(tài)特征定義，那些語義是無定義的（？）。

9.4.3.2 Structural Features（結(jié)構(gòu)特征）
A StructuralFeature is a typed Feature of a Classifier that specifies the structure of instances of the Classifier.The StructuralFeatures of a Classifier that are Properties are called the attributes of the Classifier (see 9.2.3). In UML,
Property is the only kind of StructuralFeature so all of the StructuralFeatures of a Classifier are Properties, and hence attributes.

結(jié)構(gòu)特征是類目的特征的一個種類，它定義了類目實(shí)例的結(jié)構(gòu)。類目的結(jié)構(gòu)特征是被稱為類目屬性的性質(zhì)。在UML中，性質(zhì)是結(jié)構(gòu)特征唯一的一種類型，即類目的結(jié)構(gòu)特征就是性質(zhì)，也就是屬性。

For each instance of a Classifier there is a value or collection of values for each direct or inherited non-static attribute of the Classifier, as follows:

對于類目的每個實(shí)例的直接或繼承的非靜態(tài)屬性，存在值或值的聚合，規(guī)則如下：

· If the attribute’s multiplicity is 0..1, there shall either be no value or a single value whose Type conforms to the Type of the attribute

如果屬性的多重度是0..1，則不存在或存在一個單值，值的類型符合屬性的類型。

· If the attribute’s multiplicity is 1..1, there shall be a single value whose Type conforms to the Type of the attribute.

如果屬性的多重度是1..1，應(yīng)給存在一個單值，值的類型符合屬性的類型。

· If the attribute’s multiplicity is j..k where k is not 1, there shall be a collection of values whose size is not less than j and not greater than k, each of whose Types conforms to the Type of the attribute.

如果屬性的多重都是j..k，這里k不為1，則存在一個值的聚合，聚合的大小不小于j而且不大于k，每一個類型都應(yīng)該符合屬性的類型。

· If the attribute’s multiplicity is 0..0, there shall be no value or values.

如果屬性的多重都為0..0，那么不存在值或值的聚合。

If a StructuralFeature is marked with isStatic = true, then the bullet points above are relative to the Classifier itself considered as an identifiable individual within some execution scope, rather than to individual instances. (See sub
clause 6.3.1 for a discussion of execution scope.)

如果結(jié)構(gòu)特征被標(biāo)記為isStatic=true，那么上面的要點(diǎn)就是關(guān)于類目自身的，它在某些執(zhí)行域中被被識別，而不是一個獨(dú)立的實(shí)例被識別。

In a semantically conforming tool, each inherited static StructuralFeature shall have one of two alternative semantics:

在一個語義一致的工具中，每一個繼承的靜態(tài)結(jié)構(gòu)特征應(yīng)該具有兩個可選語義

中的一個：

1.Within an execution scope, the value or collection of values of the StructuralFeature is always the same for any inheriting Classifier as its value or collection of values for the owning Classifier. These semantics correspond
to those for static members in Java and C#.

?在執(zhí)行領(lǐng)域中，結(jié)構(gòu)特征在繼承 類目中和在結(jié)構(gòu)特征的擁有者類目中的的值或者值聚合都是一樣的。這樣的語義符合Java和C#對于靜態(tài)成員的定義。

2. Within an execution scope, the StructuralFeature has a separate and in??? dependent value or collection of values for its owning Classifier and for each Classifier that inherits it. These semantics correspond to those for class
instance variables in Ruby and Smalltalk.

在執(zhí)行領(lǐng)域中，結(jié)構(gòu)特征在它的所有者類目中和繼承類目中有分離的，獨(dú)立的值或值聚合。這樣的語義符合Ruby和Smarttalk。

If a StructuralFeature is marked with isReadOnly true, then it may not be updated once it has been assigned an initial value. Conversely, when isReadOnly is false (the default), the value may be modified.

如果結(jié)構(gòu)特征被標(biāo)記為isReadOnly為真，那么一旦它被賦初值以后，就不應(yīng)該再被更新。相反地，當(dāng)isReadOnly為假（缺省值），值可以被更改。

參考資料：

《OMG Unified Modeling Language TM (OMG UML) Version 2.5》

? URL：http://www.omg.org/spec/UML/2.5