ValueType : public abstract class
Created: 2006-03-03 10:39:03
Modified: 2010-04-29 14:45:10
Project:
Advanced:
<p>From SysML:<br/></p><p><br/></p><p>A ValueType defines types of values that may be used to express information about a system, but cannot be identified as the target of any reference. Since a value cannot be identified except by means of the value itself, each such value within a model is independent of any other, unless other forms of constraints are imposed. Value types may be used to type properties, operation parameters, or potentially other elements within SysML. SysML defines ValueType as a stereotype of UML DataType to establish a more neutral term for system values that may never be given a concrete data representation. For example, the SysML "Real" ValueType expresses the mathematical concept of a real number, but does not impose any restrictions on the precision or scale of a fixed or floating-point representation that expresses this concept. More specific value types can define the concrete data representations that a digital computer can process, such as conventional Float, Integer, or String types. SysML ValueType adds an ability to carry a unit of measurement or dimension associated with the value. A dimension is a kind of quantity that may be stated in terms of defined units, but does not restrict the selection of a unit to state the value. A unit is a particular value in terms of which a quantity of the same dimension may be expressed. A SysML ValueType may define its own properties and/or operations, just as for a UML DataType.<br/></p><p><br/></p><p><br/></p><p>Semantics:<br/></p><p>The abstract metaclass ValueType defines types of values that may be used to express information about a system. The ValueType adds an ability to carry a description, a dimension associated with the value, and a unit of measure. A dimension is a kind of quantity that may be stated in terms of defined units, but does not restrict the selection of a unit to state the value. A unit is a particular value in terms of which a quantity of the same dimension may be expressed.<br/></p><p>Logical and physical datatypes cannot be distinguished on the type. The context (e.g., EnvironmentModel or FunctionalAnalysisArchitecture) decides if a speed datatype is physical or logical. On AnalysisLevel or DesignLevel, physical datatypes shall not be interpreted in the implementation sense as this would include int32, coding formula, etc.<br/></p><p><br/></p><p>Extension: UML Datatype, SysML ValueType<br/></p>
Attribute Details
public String
  description
Range:0 to 1
Notes: Description of the datatype ValueType.
public String
  dimension
Range:0 to 1
Notes: The (physical) quantity, e.g., "Speed", "Temperature".
public String
  unit
Range:0 to 1
Notes: The unit of data.<br /><br />Example: For temperature the unit may be "degree Celsius".
Object Type Connection Notes
RangeableValueType Class Generalization  
EnumerationValueType Class Generalization  
«atpType» EADatatype Class Generalization