| Integrated generic resource: Material and other engineering properties | ISO 10303-45:2019(E) © ISO |
The qualified_measure_schema specializes the resource constructs from the measure_schema and the maths_function_schema to allow quantities to be qualified, i.e. further characterized as to their type, precision, uncertainty and reliability. The qualified_measure_schema provides a particular syntax to specify the allowed formats for the numeric values that may be associated with a property.
This clause defines the information requirements to which implementations shall conform using the EXPRESS language as defined in ISO 10303-11. The following EXPRESS declaration begins the qualified_measure_schema and identifies the necessary external references.Short names of entities defined in this schema are described in Annex A. Unambiguous identification of this schema is defined in Annex B.
EXPRESS specification:
*)
SCHEMA qualified_measure_schema;
REFERENCE FROM
mathematical_functions_schema
--
ISO 10303-50
(maths_value);
REFERENCE FROM
measure_schema
--
ISO 10303-41
(measure_with_unit,
unit);
REFERENCE FROM
representation_schema
--
ISO 10303-43
(representation_item);
REFERENCE FROM
support_resource_schema
--
ISO 10303-41
(identifier,
label,
text,
bag_to_set);
(*
NOTE 1 The schemas referenced above are specified in the following parts:
mathematical_functions_schema ISO 10303-50 measure_schema ISO 10303-41 representation_schema ISO 10303-43 support_resource_schema ISO 10303-41
NOTE 2 See Annex D for a graphical representation of this schema.
A physical quantity may have several aspects other than its value and units. The value may be uncertain because of the variability in the measurement procedure, leading to a lack of reproducibility. The value of a datum may be labelled as being approved for design, for example, or otherwise characterized as to its type and status. This schema supports the addition of these concepts.
The concept of uncertainty on a measured value used in this part of ISO 10303 is taken from Clause 2.2 of ISO/IEC Guide 98:1995. In general, the result of a measurement, y, is only an approximation or estimate of the value of the specific quantity that is the subject of the measurement (the measurand), Y. The uncertainty of the result of a measurement reflects the lack of exact knowledge of the measurand and thus the result is complete only when accompanied by a quantitative statement of its uncertainty. The uncertainty generally consists of several components which may be grouped into two categories according to the method used to estimate the numerical values of the components:
Each component of uncertainty that contributes to the uncertainty of a measurement result is represented by an estimated standard deviation, termed standard uncertainty, ui , and equal to the positive square root of the estimated variance. The procedures for evaluating the standard uncertainty for both of the above categories are described in Clause 4 of ISO/IEC Guide 98:1995.
The standard uncertainty of the results of a measurement, when that result is obtained from the values of a number of other quantities, is termed the combined standard uncertainty, uc . It is the estimated standard deviation associated with the result and is equal to the positive square root of the combined variance, obtained by summing all variance and covariance components, however evaluated. The procedure for combining the variance and covariance components is described in Clause 5 of ISO/IEC Guide 98:1995. This schema provides the means for representing either the standard uncertainty or the combined standard uncertainty.
NOTE The number of measurements that have been used to derive the uncertainty of a measured value can be specified by use of the data_environment associated with the value (See Clause 5).
Although the combined standard uncertainty is used to express the uncertainty of many measurement results, what is often required is a measure of uncertainty that defines an interval about the measurement result within which the value of the measurand can be confidently asserted to lie. The measure of uncertainty intended to meet this requirement is termed the expanded uncertainty, U, and is obtained by multiplying uc(y) by a coverage factor, k. Thus U = kuc(y) and it can be confidently asserted that: y – U <=Y <= y + U, which is usually written as Y = y ± U. In general, the value of k is chosen on the basis of the desired level of confidence to be associated with the interval defined by U = kuc . Typically, k is in the range of 2 to 3. When the normal distribution applies to the results and uc has a negligible uncertainty, then k = 2 defines an interval having a level of confidence of approximately 95 percent and k = 3 defines an interval having a level of confidence greater that 99 percent.
EXPRESS specification:
*)
TYPE
value_format_type
=
identifier;
WHERE
WR1: LENGTH(SELF) <= 80;
END_TYPE;
(*
Formal propositions:
WR1: A value_format_type length shall not exceed 80.
EXPRESS specification:
*)
TYPE
value_qualifier
=
SELECT
(maths_value_precision_qualifier,
precision_qualifier,
type_qualifier,
uncertainty_qualifier,
value_format_type_qualifier);
END_TYPE;
(*
A descriptive_representation_item is a type of representation_item. A descriptive_representation_item is a text element of product data that participates in one or more representations or contributes to the definition of another representation_item.
A descriptive_representation_item contributes to the definition of another representation_item when it is either paired with another representation_item in a representation that has only two representation_items or when the representation that contains a descriptive_representation_item is related to another representation through a representation_relationship.
EXPRESS specification:
*)
ENTITY descriptive_representation_item
SUBTYPE OF (representation_item);
description : text;
END_ENTITY;
(*
Attribute definitions:
description: the value of the representation in textual form.
EXPRESS specification:
*)
ENTITY expanded_uncertainty
SUBTYPE OF (standard_uncertainty);
coverage_factor : REAL;
END_ENTITY;
(*
Attribute definitions:
coverage_factor: the multiplier of the uncertainty of the value.
EXPRESS specification:
*)
ENTITY maths_value_qualification;
name : label;
description : text;
qualified_maths_value : maths_value_with_unit;
qualifiers : SET[1:?] OF value_qualifier;
WHERE
WR1: SIZEOF(QUERY(temp <* qualifiers | ('QUALIFIED_MEASURE_SCHEMA.PRECISION_QUALIFIER' IN TYPEOF(temp)) OR ('QUALIFIED_MEASURE_SCHEMA.MATHS_VALUE_PRECISION_QUALIFIER'
IN TYPEOF(temp)))) < 2;
WR2: NOT ('REPRESENTATION_SCHEMA.REPRESENTATION_ITEM' IN TYPEOF(SELF\maths_value_qualification.qualified_maths_value));
END_ENTITY;
(*
Attribute definitions:
name: the word or group of words by which the maths_value_qualification is referred to.
description: a narrative description of the maths_value_qualification.
qualified_maths_value: the maths_value_with_unit that is to be qualified.
qualifiers: the further characterisation of the maths_value_with_unit.
Formal propositions:
WR1: At most one of the elements of the qualifiers attribute can be a precision_qualifier or a maths_value_precision_qualifier.
WR2: The entity shall not be used to associate qualifiers with a measure that is used in a complex entity instantiation along with a representation_item.
EXPRESS specification:
*)
ENTITY maths_value_representation_item
SUBTYPE OF (representation_item, maths_value_with_unit);
END_ENTITY;
(*
EXPRESS specification:
*)
ENTITY maths_value_with_unit;
value_component : maths_value;
unit_component : unit;
END_ENTITY;
(*
Attribute definitions:
value_component: the reference to the specification of the mathematical function.
unit_component: the reference to the unit quantity for the value_component.
EXPRESS specification:
*)
ENTITY measure_qualification;
name : label;
description : text;
qualified_measure : measure_with_unit;
qualifiers : SET[1:?] OF value_qualifier;
WHERE
WR1: SIZEOF(QUERY(temp <* qualifiers | ('QUALIFIED_MEASURE_SCHEMA.PRECISION_QUALIFIER' IN TYPEOF(temp)) OR ('QUALIFIED_MEASURE_SCHEMA.MATHS_VALUE_PRECISION_QUALIFIER'
IN TYPEOF(temp)))) < 2;
WR2: NOT ('REPRESENTATION_SCHEMA.REPRESENTATION_ITEM' IN TYPEOF(SELF\measure_qualification.qualified_measure));
END_ENTITY;
(*
Attribute definitions:
name: the word or group of words by which the measure_qualification is referred to.
description: a narrative description of the measure_qualification.
qualified_measure: the measure_with_unit that is to be qualified.
qualifiers: the further characterization of the measure_with_unit.
Formal propositions:
WR1: At most one of the elements of the qualifiers attribute can be a precision_qualifier or a maths_value_precision_qualifier.
WR2: The entity shall not be used to associate qualifiers with a measure that is used in a complex entity instantiation along with a representation_item.
EXPRESS specification:
*)
ENTITY measure_representation_item
SUBTYPE OF (representation_item, measure_with_unit);
END_ENTITY;
(*
EXPRESS specification:
*)
ENTITY maths_value_precision_qualifier;
precision_value : maths_value;
END_ENTITY;
(*
Attribute definitions:
precision_value: the number of significant figures of the components of the value.
EXPRESS specification:
*)
ENTITY precision_qualifier;
precision_value : INTEGER;
END_ENTITY;
(*
Attribute definitions:
precision_value: the number of significant figures of the value.
EXPRESS specification:
*)
ENTITY qualified_representation_item
SUBTYPE OF (representation_item);
qualifiers : SET[1:?] OF value_qualifier;
WHERE
WR1: SIZEOF(QUERY(temp <* qualifiers | ('QUALIFIED_MEASURE_SCHEMA.PRECISION_QUALIFIER' IN TYPEOF(temp)) OR ('QUALIFIED_MEASURE_SCHEMA.MATHS_VALUE_PRECISION_QUALIFIER'
IN TYPEOF(temp)))) < 2;
END_ENTITY;
(*
Attribute definitions:
qualifiers: the further characterization of the representation_item.
Formal propositions:
WR1: At most one of the elements of the qualifiers attribute can be a precision_qualifier or a maths_value_precision_qualifier.
EXPRESS specification:
*)
ENTITY qualitative_uncertainty
SUBTYPE OF (uncertainty_qualifier);
uncertainty_value : text;
END_ENTITY;
(*
Attribute definitions:
uncertainty_value: the qualitative uncertainty of the value.
EXAMPLE Expected values for uncertainty_value include: 'low', 'medium', 'high'.
EXPRESS specification:
*)
ENTITY standard_uncertainty
SUPERTYPE OF (expanded_uncertainty)
SUBTYPE OF (uncertainty_qualifier);
uncertainty_value : REAL;
END_ENTITY;
(*
Attribute definitions:
uncertainty_value: the quantitative uncertainty of the value.
A type_qualifier is the specification of a type of a datum.
NOTE Legal values and constraints for the attribute are specified in application protocols. Typical values for the attribute may include: 'measured', 'calculated', 'nominal', 'maximum', 'minimum', 'theoretical', 'remainder', 'design-allowable', 'combined', 'A-basis statistical', 'B-basis statistical' and 'arithmetic mean'.
EXPRESS specification:
*)
ENTITY type_qualifier;
name : label;
END_ENTITY;
(*
Attribute definitions:
name: the word or group of words by which the type or reliability of the value is referred to.
EXPRESS specification:
*)
ENTITY uncertainty_qualifier
SUPERTYPE OF (ONEOF (standard_uncertainty,
qualitative_uncertainty));
measure_name : label;
description : text;
END_ENTITY;
(*
Attribute definitions:
measure_name: specifies the kind of measure for which the entity defines the uncertainty.
EXAMPLE Expected values for measure_name include: 'distance uncertainty', 'angular uncertainty', 'curvature uncertainty'.
description: the description of the uncertainty of the value.
A value_format_type_qualifier is the specification of the length and pattern of the recommended presentation on media of a value, including exchange data explicit format. A value_format_type_qualifier is derived from the Value Format as described in ISO 13584-42 and is renamed in this part of ISO 10303 for consistency with other parts of ISO 10303. Implementations shall be in conformance with ISO 13584-42 when exchanging or storing members of value_format_type_qualifier with the exception of NR5 format which is defined in this part of ISO 10303. D.1 in ISO 13584-42 specifies the subset of the ISO/IEC 14977 EBNF syntactic metalanguage used to specify the value format of properties. The grammar for NR2 and NR5 format is included herein.
NOTE 1 ISO 13584-42 is not part of the integrated resources of ISO 10303; therefore, the EXPRESS declarations, meta-identifiers and grammar are included in this part of ISO 10303.
NOTE 2 The primary purpose for inclusion in this part of ISO 10303 is to support representation of the format of quantitative data types. Legal values and constraints for the attribute are specified in application protocols. Typical values for the attribute may include real numbers with decimal-mark value format NR2 or NR5.
NOTE 3 The NR5 format coding is identical to NR2 format with the following exception: the interpretation of the variable length indicator '..' is limited to control the number of digits after the decimal-mark. The NR5 format coding asserts no control over the number of digits preceding the decimal-mark.
The meta-identifiers used in the grammar that define the various value formats are the following:
NR2-value format The NR2-value syntax specifies the format of a real property value that does not need an exponent.
Syntax rule: NR2Value = 'NR2', ((signedNumber, variableLengthIndicator) | (signedNumber, space) | variableLengthIndicator | space), lengthOfIntegralPart, decimalMark, lengthOfFractionalPart;
The meaning of NR2-value format components for value representation is as follows:
NOTE 4 NR2 number values shall not contain any spaces.
NOTE 5 If preceded by a variableLengthIndicator the actual number of digits of the fractional part may be less.
NOTE 6 If preceded by a variableLengthIndicator the actual number of digits of the integral part may be less.
NOTE 7 It is valid for both the number of digits for the integral and fractional parts to be less than their respective specifications concurrently.
Syntax rule: NR5Value = 'NR5', ((signedNumber, variableLengthIndicator) | (signedNumber, space) | variableLengthIndicator | space), lengthOfFractionalPart;
The meaning of NR5-value format components for value representation is as follows:
NOTE 8 NR5 number values shall not contain any spaces.
NOTE 9 If preceded by a variableLengthIndicator the actual number of digits of the fractional part may be less.
EXAMPLE 1 The format of the real number 2.00 may be represented as "NR2 3.3" where the physical file presentation would be '002.00'.
EXAMPLE 2 The format of the real number 2.00 may be represented as "NR2..3.3" where the physical file presentation would be '2.00'.
EXAMPLE 3 The physical representations '321.233', '1.234', '23.56', '9.783', '0.72' and '.72' all comply with the "NR2..3.3" code.
EXAMPLE 4 The format of a set of real numbers each of whom has 3 digits after the decimal-mark may be represented as "NR5 3" for an unsigned number and "NR5S 3" for a signed number.
EXAMPLE 5 The format of a set of real numbers each of whom has no more than 3 digits after the decimal-mark may be represented as "NR5..3" for unsigned and "NR5S..3" for signed numbers.
EXPRESS specification:
*)
ENTITY value_format_type_qualifier;
format_type : value_format_type;
END_ENTITY;
(*
Attribute definitions:
format_type: the code for the format type.
*)
END_SCHEMA; -- qualified_measure_schema
(*
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