1、ICS 25.040.40 Ref. No. ISO 10303-108:2005/Cor.1:2008(E) ISO 2008 All rights reserved Published in Switzerland INTERNATIONAL STANDARD ISO 10303-108:2005 TECHNICAL CORRIGENDUM 1 Published 2008-12-15 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATIONIndustrial a
2、utomation systems and integration Product data representation and exchange Part 108: Integrated application resource: Parameterization and constraints for explicit geometric product models TECHNICAL CORRIGENDUM 1 Systmes dautomatisation industrielle et intgration Reprsentation et change de donnes de
3、 produits Partie 108: Ressources dapplication intgres: Paramtrage et contraintes pour les modles de produits gomtriques explicites RECTIFICATIF TECHNIQUE 1 Technical Corrigendum 1 to ISO 10303-108:2005 was prepared by Technical Committee ISO/TC 184, Automation systems and integration, Subcommittee S
4、C 4, Industrial data. Introduction The modifications made to ISO 10303-108:2005 have three purposes: a) to remove an entity name clash with ISO 10303-210:2001 (published earlier than ISO 10303-108:2005 and therefore having prior claim on the name) concerning model_parameter. This Technical Corrigend
5、um provides for its replacement throughout ISO 10303-108 with variational_parameter; b) to remove the definition of non_negative_length_measure, which has been moved to ISO 10303-41, and to replace it by a reference to that resource; c) to correct minor errors in EXPRESS code. The opportunity has al
6、so been taken to update the normative reference to ISO 10303-55 (now published) and to correct a few minor editorial errors mainly concerning the numbering of notes and examples. ISO 10303108:2005/Cor.1:2008(E) Modications to the text of ISO 10303108:2005 Table of Contents, p. iii ff. The term model
7、_parameter is being systematically replaced by variational_parameter. The necessary entity name change requires replacement of the titles of several subclauses. Make the following replacements: Subclause: Previous title: New title: 4.2.1 Model parameters Variational parameters 4.4.1 model_parameter
8、variational_parameter 4.4.2 bound_model_parameter bound_variational_parameter 4.4.3 unbound_model_parameter unbound_variational_parameter 4.4.7 unbound_model_parameter_semantics unbound_variational_parameter_semantics 5.2.5 Roles of model parameters. . . Roles of variational parameters. . . Delete t
9、he entry 7.3.10 non_negative_length_measure from the Table of Contents Clause 1, p. 1 Replace model parameters by variational parameters in line 1 of the rst paragraph, and lines 1 and 3 of the second paragraph. Clause 1.1, p. 3 Replace model parameters by variational parameters in the third bullete
10、d item of this subclause. Clause 2, p. 5 ISO 1030355 has now been published. After ISO 1030355delete :, and also delete the footnote. Clause 3.7.24, p. 11 Replace model parameter by variational parameter, and reposition this denition in the list to follow the denition of variational (previously clau
11、se 3.7.34). The wording of the denition is unchanged, but the text of the notes and the example needs to be changed. Replace NOTE 1, EXAMPLE and NOTE 2 as follows: NOTE 1 Assignment of different values to variational parameters generates different members of a family of models. Variational parameter
12、s therefore express design freedom in a model, according to the parameterization scheme imposed by its creator. Limitations may be dened on the allowable ranges of variational parameters. EXAMPLE The dimensions of a generic block may be represented by variational parameters L (length), W (width) and
13、H (height). Individual members of the family of blocks are specied by assigning numerical values to the three parameters independently. Alternatively, relationships may be dened between the variational parameters, such as L = 2W;H = 0:5W , to restrict the size of the family and dene it in terms of t
14、he single independent variational parameterW . NOTE 2 Distinction must be made between the use of the word parameter in this part of ISO 10303, in ISO 1030311, in ISO 1030342 and in ISO 1030350. In ISO 1030311 a parameter is used for the formal represen tation of an input to, or output from, a funct
15、ion or procedure dened in an EXPRESS schema. In ISO 1030342 a parameter is a variable used to identify the position of a point on a curve or a surface, so that the parameter may be thought of as an input to a function whose output is a coordinate value. In ISO 1030350 a parameter is dened as a free
16、variable in an expression. In this part of ISO 10303 the term variational parameter is used for a variable that controls dimensions or other gross characteristics of a model, for example the overall shape of a product model. A variational parameter may be thought of as an input to a procedure, in th
17、is case a procedure that 2 c ISO 2008 All rights reservedISO 10303108:2005/Cor.1:2008(E) computes one instance of a family of shape models. It is unfortunate that the word parameter is in widespread current use for such a variety of purposes. Although at a broad conceptual level the usages within IS
18、O 10303 are similar, there are signicant differences in such matters as the way the functions or procedures are dened and in the scope of parameters in a model. Clause 3.7 more generally The terms dened in this clause need to be reordered into alphabetical order, and other references to the supersed
19、ed entity name need to be changed as follows: (a) Renumber clause 3.7.24, as modied above, to 3.7.34; (b) Renumber the current clauses 3.7.25 3.7.34 as 3.7.24 3.7.33, keeping their sequence the same; (c) In the clause newly numbered 3.7.25, dening the term parameter, replace the existing denition by
20、 variational parameter (in the context of this part of ISO 10303) see the denition of variational parameter given in clause 3.7.34. Clause 4, p. 15 Clause 4.2 and most of clause 4.4 need to be replaced. Subclauses 4.1 and 4.3 may remain as they are (subject to the correction noted below), and so may
21、 subclause 4.5. Clause 4.4.9 needs only one name replacement. Clause 4.1, p. 15 In NOTE 2, replace Figure by Figures. Clause 4.2, p. 15 Replace subclause 4.2 by the following: 4.2 Fundamental concepts and assumptions This schema provides representation methods for the following: Variables, represent
22、ed by instances of bound_variational_parameter or unbound_variational_ parameter, expressing variation or design freedom in a representation or model; A means for binding a bound_variational_parameter instance to an attribute of another entity data type instance in the same representation; Domains o
23、f validity for instances of bound_variational_parameter and unbound_variational_ parameter; A means for xing the values of attributes of specic entity data type instances in a model, equiva lent to the use of bound_variational_parameter instances with constant associated values. These resource const
24、ructs are of general utility in the exchange and sharing of ISO 10303 models em bodying the capability for variation of attribute values in a model following an exchange; the capture and transfer of constraint relationships dened in terms of mathematical expressions, functions or procedures. Specica
25、lly, variational parameters can participate in instances of free_ form_constraint as dened in clause 5.4.4. Clause 6.3.1 of this part of ISO 10303 denes variational_representation_item as a subtype of the ISO 1030343 entity data typerepresentation_item. Variational parameters are dened as subtypes o
26、f c ISO 2008 All rights reserved 3ISO 10303108:2005/Cor.1:2008(E) variational_representation_item, which is the supertype of all entity data types used to express the variational aspects of models with explicit parameterization and constraints. The type of representation in which they participate is
27、 a variational_representation, as dened in clause 6.3.3. 4.2.1 Variational parameters An abstract entity data type variational_parameter is provided, with two instantiable subtypes, bound_ variational_parameter and unbound_variational_parameter. These allow for the capture and trans mission of permi
28、tted aspects of model variation that can be exploited in a receiving system. A bound_ variational_parameter is bound to an attribute of an entity data type instance in an ISO 10303 model, in which case it provides a syntactic representation of the value of that attribute, for example a dimensional v
29、alue. By contrast, an unbound_variational_parameter is not directly associated with any model at tribute. Either kind of variational_parameter may be used in mathematical relationships dened in freeform constraints. The current value of avariational_parameter is specied by one of its attributes; in
30、the bound case the value of this attribute is required by an informal proposition to be the same as the value of the attribute to which it is bound. The entity data type variational_parameter is dened as a subtype of variational_representation_ item, and the scope of its instantiable subtypes is the
31、refore dened by those instances of variational_ representation in which they participate. It is also a subtype of the ISO 1030350 entity data type maths_variable, from which it inherits an attribute values_space, of ISO 1030350 typemaths_space. This attribute species the domain of validity for value
32、s of the variational_parameter. These may include domains corresponding to those of the EXPRESS data types REAL, INTEGER, BOOLEAN and STRING, together with various bounded subsets of the REAL and INTEGER domains. This part of ISO 10303 does not directly provide the use of parameters having values be
33、longing to aggregate types, but applications may dene such extensions if they are required. EXAMPLE 1 Consider a rectangle, with length x units and width y units. Here x and y are variables or parameters. An explicit constraint relationship x = y 2 + 2 relates these dimensions. Valid parameter range
34、s 10:0 x 30:0 and 2:0 y 5:0 are dened. In this case the two variables correspond to instances of bound_variational_parameter, both bound to physical quantities in the model, i.e., dimensional attributes of the rectangle. The parameterization and constraint information may be transmitted together wit
35、h a current result an explicit model of a rectangle with length 18.0 units and width 4.0 units. These parameter values satisfy the constraint and fall within the required parameter ranges. When model transfer is complete, if one of the parameters is edited the other should adjust accordingly to main
36、tain satisfaction of the constraint, provided the parameters remain within their valid ranges. It is assumed that the necessary functionality for parameter variation and constraint maintenance will be provided by the receiving system. The following example illustrates the use of an unbound_variation
37、al_parameter. EXAMPLE 2 Suppose an instance of right_circular_cylinder (as dened in ISO 1030342), has associated instances of bound_variational_parameter associated with its radius and height attributes, here denoted by r andh respectively. A third parameter, denoted byt, may be used to control the
38、values of bothr andh according to the relationshipsr = 3t2,h = t 2 +1. In the case whent is not bound to an attribute of any entity data type instance, it will appropriately be modelled in terms of an unbound_variational_parameter. 4.2.2 Parameter binding to an instance attribute A bound_variational
39、_parameter is associated with an attribute of an entity data type instance in a populated schema, whose value represents the value of the parameter. This association is dened through the use of an entity data type instance_attribute_reference that simply species the name of an attribute 4 c ISO 2008
40、 All rights reservedISO 10303108:2005/Cor.1:2008(E) and the instance to which it belongs (see clause 4.4.6). A simple example is given below to illustrate the principle, and the intended usage of the mechanism is more fully documented in clause F.1 of annex F. Once the parameter binding has been est
41、ablished, the parameter may participate in a relationship that governs its value if the model is subsequently edited in a receiving system. EXAMPLE For the purpose of the example, entity data types dened in the ISO 10303 integrated generic re sources are treated as though they are instantiable eleme
42、nts in an application protocol. It is desired to parameterize one dimension of a block solid, as dened in ISO 1030342. This has three attributes, x,y andz, that prescribe its three principal dimensions. In any instantiation of the block these will have specic real numerical values. Consider now the
43、following fragment of an ISO 1030321 transfer le: #290 = AXIS2_PLACEMENT_3D(.); #300 = BLOCK(BLOCK1, #290, 4.0, 6.0, 8.0); #310 = INSTANCE_ATTRIBUTE_REFERENCE (GEOMETRIC_MODEL_SCHEMA.BLOCK.X, #300); #320 = FINITE_REAL_INTERVAL(2.0, .CLOSED., 10.0, .CLOSED.); #330 = BOUND_VARIATIONAL_PARAMETER (XPARA
44、M, #320, XPARAM, BLOCK XDIMENSION, * ); #340 = BOUND_PARAMETER_ENVIRONMENT(#310, #330); The instances represented above are explained as follows: #290: denes an ISO 1030342 axis placement (details omitted) for the next instance; #300: the block instance. As a subtype of ISO 1030343 representation_it
45、em, this inherits a name at tribute of type label, whose value in this instance isblock1. The block is dened with respect to the axis placement#290 and has dimensions 4.0, 6.0 and 8.0 units; #310: an instance of instance_attribute_reference;geometric_model_schema.block.x is the specied attribute nam
46、e and the referenced block instance is#300. Note that the attribute name appears fully qualied with the name of the owning entity data type and its dening schema. This entry in the le identies the particular instance whose specied attribute is to be associated with the bound_variational_parameter in
47、stance; #320: denes the domain of that parameter, a real interval closed at both ends, bounded below by 2.0 and above by 10.0. The entity data type nite_real_interval is dened in ISO 1030350; #330: species the bound_variational_parameter itself, as dened in clause 4.4.2 of this schema. Its attribute
48、 value list contains these entries: a label,xparam, corresponding to the name attribute of its representation_item supertype; a domain#320, corresponding to the values_space attribute of its maths_variable supertype; a label, xparam, corresponding to the name attribute of its maths_variable supertyp
49、e the two inherited name attributes are required by a WHERE rule to have the same values; a textual descriptionblock xdimension; the value of the variational_parameter, given as a derived value, although no formal method is avail able in EXPRESS for deriving it from instance#300; #340: an instance of bound_parameter_environment, den
