Life cycle data for process plant: Reference data for observations and measurements: 4.3 Information


Life cycle data for process plant: Reference data for observations and measurements	ISO/WD 15926-x:200x(E)

Cover page
Table of contents
Copyright
Foreword
Introduction
1	Scope
2	Normative references
3	Terms, definitions, abbreviations and symbols

4	Observations and measurements reference data
	4.1	Introduction to observations and measurements reference data
	4.2	Observing activity
	4.3	Information
	4.4	Temporal part and time
	4.5	Variation of property
	4.6	Monitoring activity
	4.7	Monitoring criterion

A	Information object registration
B	Document URN
C	Reference data relationships
D	Reference data as OWL
E	Temporal part example
Bibliography
Index

4.3 Information

4.3.1 What is information

4.3.1.1 Information content and information carrier

A iso15926-2:possible_individual can bear a pattern that can be decoded by a person, by a machine or by a person using a machine. Such a iso15926-2:possible_individual is an information_carrier.

An information_carrier can be classified according to the nature of the response made by a person, machine or person using a machine that decodes it. A class that consists of all information carriers that produce the same response is an information_content.

An information_content can be a class that consists of all copies of a file.

NOTE 1 An information_carrier can be a computer file that is identified by a path on a computer system, or by a URI on the Internet. A computer file is not usually thought of as "physical", but:

it exists in time - a computer file is created and subsequently destroyed or deleted;
it exists in space - a computer file held by a computer or network of computers, which is located somewhere;
it is made up of matter - a computer file is destroyed when a computer is destroyed, in the same way that a book is destroyed when a library is destroyed.

NOTE 2 An information_carrier can be a signal, which is transmitted from a sender to a receiver.

A signal is not usually thought of a "physical", but it is something that can be detected by an instrument and that exists during a period of time. A signal is a iso15926-2:stream that is also a iso15926-2:possible_individual.

EXAMPLE 1 The English language printed copy of the UN "Universal declaration of human rights" possessed by Fred Bloggs is an information_carrier. This can be decoded by any sighted, literate, English language speaking person.

EXAMPLE 2 The file http://www.un.org/Overview/rights.html is an information_carrier. This can be decoded by a Web browser, where "decoding" is defined as generating a human readable presentation.

This can be decoded by an English language speaking person using a Web browser, where "decoding" is defined as understanding the intention of UN resolution 217 A (III) of 1948-12-10.

EXAMPLE 3 The class of all information carriers that can lead to an understanding of the UN "Univeral declaration of human rights" by a person who only speaks English is an information_content. We can call this class "UN Universal declaration of human rights document in English".

The English language printed copy of the UN "Universal declaration of human rights" possessed by Fred Bloggs is a member if this class.

The file http://www.un.org/Overview/rights.html is also a member of this class. The file http://www.unhchr.ch/udhr/lang/eng.htm is yet another member of this class. In this case, there are at least two instances of information_carrier on the Web with the same information_content.

EXAMPLE 4 The class of all information carriers that can lead to an understanding of the UN "Universal declaration of human rights" is an information_content. We can call this class "UN Universal declaration of human rights document".

The English language printed copy of the UN "Universal declaration of human rights" possessed by Fred Bloggs is a menber if this class.

The file http://www.un.org/Overview/rights.html is also a member of this class. It can be decoded by any English language speaking person using a Web browser.

The file http://www.unhchr.ch/udhr/lang/wls.htm is a member of this class. It can be decoded by any Welsh (Cymraeg) language speaking person using a Web browser.

EXAMPLE 5 The class of all information carriers that reproduce the UN "Universal declaration of human rights" with the same format as the official record of the 1948-12-10 session of the UN General Assembly is a information_content. We can call this class "UN Universal declaration of human rights reproduction of official record".

The printed copy of the record of the 1948-12-10 session of the UN General Assembly possessed by the UK Foreign Office is a menber if this class. It can be decoded by any sighted person.

The file http://daccess-ods.un.org/access.nsf/Get?Open&DS=A/RES/217(III)&Lang=E is a member of this class. It can be decoded by any web browser that supports PDF.

EXAMPLE 6 The class of all copies of http://www.un.org/Overview/rights.html is an information_content. We can call this class "Copy of UN Universal declaration of human rights from UN website".

The file C:\useful_documents\UN_declaration_of_human_rights.html on the computer possessed by Fred Bloggs is a member of this class.

4.3.1.2 Statement and formula

A statement is neither an information_content nor an information_carrier.

NOTE 1 An RDF Statement is http://www.w3.org/1999/02/22-rdf-syntax-ns#Statement.

A set of statements is called a "formula" or "graph".

NOTE 2 A set of statements may be one or more graphs of related objects. Hence the term "formula" is prefered in this part of ISO 15926.

NOTE 3 A formula is identified as http://www.w3.org/2000/10/swap/log#Formula within the Semantic Web Application Platform - SWAP.

A formula can be recorded on an information_carrier.

EXAMPLE 1 The statement "Janet loves John" is a simple formula. This formula can be recorded by members of three different instances of information_content as follows:

the image containing the RDF diagram in Figure 3;
the XML serialisation shown below;
the N3 serialisation shown below.

GIF file:

Figure 3: Janet loves John RDF graph

XML serialisation:

<rdf:RDF xmlns:relationship="http://www.example.com/relationship/">
 <owl:Thing rdf:about="http://www.example.com/person/Janet">
  <relationship:loves rdf:about="http://www.example.com/person/John"/>
 </owl:Thing>
</rdf:RDF>

N3 serialisation:

@prefix  person        <http://www.example.com/relationship> .
@prefix  relationship  <http://www.example.com/person> .

person:Janet  relationship:loves  person:John .

4.3.1.3 Information content, information carrier and formula on the Web

Anything can be identified by an HTTP URI. The organization that assigns the URI can support dereferencing. Dereferencing obtains a "representation" of the identified thing. The organisation that assigns the URI can choose the form of the representation. Two common possibilities are:

a file that describes the thing in a format understood by Web browsers, such as HTML or PDF;

an RDF formula.

NOTE Both types of representation can be provided, and an application can choose the desired representation using "content negotiation". This is described in "Cool URIs for the Semantic Web" (http://www.w3.org/TR/cooluris/).

An information_carrier, an information_content and a formula can each be a Web resource identified by an HTTP URI. Specific types of representation can be provided, as follows:

information_carrier

If an information_carrier is a computer file, then dereferencing can obtain the content of that file.

NOTE 1 This is the expected response. If the file has the URI http://www.example.com/document/interesting_stuff.pdf then a user may reasonably expect that dereferencing will result in the document being copied to his or her computer and displayed using an PDF viewer.

If the file has the URI http://www.example.com/you-have-got-to-see-this/amazing.wmv, then a user may discover that something other than an WMV file is copied to his or her computer. The user may not be surprised, but may reasonably be disappointed.

NOTE 2 Because an information_carrier has a particular format, it is usual to indicate the format by a file name extension, such as ".htm" or ".pdf". The use of file name extensions is deprecated in "Cool URIs don't change" (http://www.w3.org/Provider/Style/URI). Implicitly this is a recommendation that a URI identifies an information_content rather than an information_carrier.

information_content

Dereferencing information_content can obtain the content, only if an information_carrier exists that carries it in a particular format. Hence dereferencing has an information_content has stages as follows:

the request is redirected to an information_carrier;
the content of the information_carrier is copied to the user's computer.

NOTE 3 The organisation that assigns a URI to an information_content can change the information_carrier to which references are redirected as it sees fit.

A reference to http://www.example.com/content/MyContent can be redirected to http://www.example.com/content/MyContent.pdf on 2008-08-12 and to http://www.example.com/content/MyContent.htm on 2008-08-13. The organisation that assigns the URI should ensure that both instances of information_carrier carry the same content, but has to be trusted.

formula

Dereferencing a formula can obtain a representation, only if an information_carrier exists that carries a representation in a particular format. Hence dereferencing has a formula has stages as follows:

the request is redirected to an information_carrier;
the content of the information_carrier is a representation of the formula, which is copied to the user's computer.

NOTE 4 The organisation that assigns a URI to a formula can change the information_carrier to which references are redirected as it sees fit.

A reference to http://www.example.com/content/MyFormula can be redirected to http://www.example.com/content/MyFormula.xml on 2008-08-12 and to http://www.example.com/content/MyFormula.n3 on 2008-08-13. The organisation that assigns the URI should ensure that both instances of information_carrier carry representations of the same formula, but has to be trusted.

4.3.1.4 Creation and use of information

An iso15926-2:activity can use and create information. The information used or created is encoded on an information_carrier that is an input to, or output from, the iso15926-2:activity.

The "provenance" of information is the iso15926-2:activity that created its first information_carrier.

EXAMPLE Consider the human observation example in clause Observing activity. The record of the observation can give provenance for the computer file http://www.example.com/observation/MyBearing_2007-03-15T16:00/record, as follows:

[ a                   iso15926-x:observing_activity ;
  iso15926-x:observation_performed_by  :Fred_Bloggs ;
  iso15926-x:during   [ iso15926-x:has_nominal_value
                           [ iso15926-x:utc_iso8601 "2007-03-15T16:00" ] ]
]
  iso15926-x:observes    :MyBearing ;
  iso15926-x:gives_result_record
                http://www.example.com/observation/MyBearing_2007-03-15T16:00/record .

The record of the observation can give provenance for the formula http://www.example.com/observation/MyBearing_2007-03-15T16:00/formula, as follows:

[ a                   iso15926-x:observing_activity ;
  iso15926-x:observation_performed_by  :Fred_Bloggs ;
  iso15926-x:during   [ iso15926-x:has_nominal_value
                           [ iso15926-x:utc_iso8601 "2007-03-15T16:00" ] ]
]
  iso15926-x:observes    :MyBearing ;
  iso15926-x:gives_result_formula
                http://www.example.com/observation/MyBearing_2007-03-15T16:00/formula .

4.3.1.5 Information about things

A thing can be associated with:

an information_carrier that has information_content that can be interpreted to obtain an understanding of the thing (see is_described_by_record);
an information_content that can be interpreted to obtain an understanding of the thing (see is_described_by);
a formula that contains statements about the thing (see is_mentioned_in).

EXAMPLE 1 The information that "Janet loves John" can be regarded as information about either Janet or John. If this information is held in the information_carrier http://www.example.com/gossip/janet_and_john.htm, then the association between the information and the people can be recorded as follows:

person:Janet  iso15926-x:is_described_by_record
                      <http://www.somewhere.org/gossip/janet_and_john.htm> .

person:John   iso15926-x:is_described_by_record
                      <http://www.somewhere.org/gossip/janet_and_john.htm> .

The formula http://www.example.com/gossip/janet_and_john.formula is:

@prefix  person        <http://www.example.com/relationship> .
@prefix  relationship  <http://www.example.com/person> .

person:Janet  relationhip:loves  person:John .

The formula can be associated with Janet and John as follows:

person:Janet  iso15926-x:is_mentioned_in
                      <http://www.somewhere.org/gossip/janet_and_john/formula> .

person:John   iso15926-x:is_mentioned_in
                      <http://www.somewhere.org/gossip/janet_and_john/formula> .

4.3.2 Information ontology

4.3.2.1 information_carrier

An object is a information_carrier if and only if:

it is a iso15926-2:possible_individual;
it bears a pattern that can be decoded by a person, by a machine, or by a person using a machine.

NOTE OWL specification:

-->
<owl:Class rdf:about="&iso15926-x;information_carrier">
 <rdfs:subClassOf rdf:resource="&iso15926-2;possible_individual"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#information_carrier"/>
</owl:Class>
<!--

4.3.2.2 information_content

An object is a information_content if and only if:

it is a iso15926-2:class_of_individual;
it consists of each member of information_carrier that produces a particlar class of response when decoded by a person, machine, or person using a machine.

The class information_content is the same as iso15926-4:information, and a subclass of iso15926-2:class_of_information_representation.

NOTE OWL specification:

-->
<owl:Class rdf:about="&iso15926-x;information_content">
 <owl:sameAs rdf:resource="&iso15926-4;information"/>
 <rdfs:subClassOf rdf:resource="&owl;Class"/>
 <rdfs:subClassOf>
  <owl:Restriction>
   <owl:onProperty rdf:resource="&rdfs;subClassOf"/>
   <owl:hasValue rdf:resource="&iso15926-x;information_carrier"/>
  </owl:Restriction>
 </rdfs:subClassOf>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#information_content"/>
</owl:Class>
<!--

4.3.2.3 creates_content

An object is a creates_content relationship if and only if:

it is a basics:mapping between iso15926-2:activity and information_content;
the content is created by the iso15926-2:activity.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;creates_content">
 <rdfs:domain rdf:resource="&iso15926-2;activity"/>
 <rdfs:range rdf:resource="&iso15926-x;information_content"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#creates_content"/>
</owl:ObjectProperty>
<!--

4.3.2.4 content_created_by

An object is a content_created_by relationship if and only if:

it is the inverse of creates_content.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;content_created_by">
 <owl:inverseOf rdf:resource="&iso15926-x;creates_content"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#content_created_by"/>
</owl:ObjectProperty>
<!--

4.3.2.5 reads_content

An object is a reads_content relationship if and only if:

it is a basics:mapping between iso15926-2:activity and information_content;
the content is read by the iso15926-2:activity.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;reads_content">
 <rdfs:domain rdf:resource="&iso15926-2;activity"/>
 <rdfs:range rdf:resource="&iso15926-x;information_content"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#reads_content"/>
</owl:ObjectProperty>
<!--

4.3.2.5 content_read_by

An object is a content_read_by relationship if and only if:

it is the inverse of reads_content.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;content_read_by">
 <owl:inverseOf rdf:resource="&iso15926-x;reads_content"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#content_read_by"/>
</owl:ObjectProperty>
<!--

4.3.2.6 creates_record

An object is a creates_record relationship if and only if:

it is a basics:mapping between iso15926-2:activity and information_carrier;
the content of the information_carrier is created by the iso15926-2:activity.

NOTE 1 If the information_carrier is a dereferencable Web resource, then identification of the information_content and use of the relationship creates_content is recommended, as described in note 2 of Information content, information carrier and formula on the Web.

NOTE 2 OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;creates_record">
 <rdfs:domain rdf:resource="&iso15926-2;activity"/>
 <rdfs:range rdf:resource="&iso15926-x;information_carrier"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#creates_record"/>
</owl:ObjectProperty>
<!--

4.3.2.7 record_created_by

An object is a record_created_by relationship if and only if:

it is the inverse of creates_record.

NOTE 1 If the information_carrier is a dereferencable Web resource, then identification of the information_content and use of the relationship content_created_by is recommended, as described in note 2 of Information content, information carrier and formula on the Web.

NOTE 2 OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;record_created_by">
 <owl:inverseOf rdf:resource="&iso15926-x;creates_record"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#record_created_by"/>
</owl:ObjectProperty>
<!--

4.3.2.8 reads_record

An object is a reads_record relationship if and only if:

it is a basics:mapping between iso15926-2:activity and information_carrier;
the content of the information_carrier is read by the iso15926-2:activity.

NOTE 1 If the information_carrier is a dereferencable Web resource, then identification of the information_content and use of the relationship reads_content is recommended, as described in note 2 of Information content, information carrier and formula on the Web.

NOTE 2 OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;reads_record">
 <rdfs:domain rdf:resource="&iso15926-2;activity"/>
 <rdfs:range rdf:resource="&iso15926-x;information_carrier"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#reads_record"/>
</owl:ObjectProperty>
<!--

4.3.2.9 record_read_by

An object is a record_read_by relationship if and only if:

it is the inverse of reads_record.

NOTE 1 If the information_carrier is a dereferencable Web resource, then identification of the information_content and use of the relationship content_read_by is recommended, as described in note 2 of Information content, information carrier and formula on the Web.

NOTE 2 OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;record_read_by">
 <owl:inverseOf rdf:resource="&iso15926-x;reads_record"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#record_read_by"/>
</owl:ObjectProperty>
<!--

4.3.2.10 has_content

An object is a has_content relationship if and only if:

it is a basics:mapping between information_carrier and information_content;
the information_carrier carries the information_content.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;has_content">
 <rdfs:domain rdf:resource="&iso15926-x;information_carrier"/>
 <rdfs:range rdf:resource="&iso15926-x;information_content"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#has_content"/>
</owl:ObjectProperty>
<!--

4.3.2.11 has_content_literal

An object is a has_content_literal relationship if and only if:

it is a basics:mapping between information_carrier and text;
the information_carrier carries the text.

NOTE OWL specification:

-->
<owl:DatatypeProperty rdf:about="&iso15926-x;has_content_literal">
 <rdfs:domain rdf:resource="&iso15926-x;information_carrier"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#has_content_literal"/>
</owl:DatatypeProperty>
<!--

4.3.2.12 is_described_by

An object is a is_described_by relationship if and only if:

it is a basics:mapping between iso15926-2:thing and information_content;
the content can be interpreted to gain understanding about the iso15926-2:thing.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;is_described_by">
 <rdfs:domain rdf:resource="&owl;Thing"/>
 <rdfs:range rdf:resource="&iso15926-x;information_content"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#is_described_by"/>
</owl:ObjectProperty>
<!--

4.3.2.13 describes

An object is a describes relationship if and only if:

it is the inverse of is_described_by.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;describes">
 <owl:inverseOf rdf:resource="&iso15926-x;is_described_by"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#describes"/>
</owl:ObjectProperty>
<!--

4.3.2.14 is_described_by_record

An object is a is_described_by_record relationship if and only if:

it is a basics:mapping between iso15926-2:thing and information_carrier;
the content of the information_carrier can be interpreted to gain understanding about the iso15926-2:thing.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;is_described_by_record">
 <rdfs:domain rdf:resource="&owl;Thing"/>
 <rdfs:range rdf:resource="&iso15926-x;information_carrier"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#is_described_by_record"/>
</owl:ObjectProperty>
<!--

4.3.2.15 record_describes

An object is a record_describes relationship if and only if:

it is the inverse of is_described_by_record.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;record_describes">
 <owl:inverseOf rdf:resource="&iso15926-x;is_described_by_record"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#content_describes"/>
</owl:ObjectProperty>
<!--

4.3.2.16 is_mentioned_in

An object is a is_mentioned_in relationship if and only if:

it is a basics:mapping between iso15926-2:thing and formula;
the formula contains a statement about the iso15926-2:thing.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;is_mentioned_in">
 <rdfs:domain rdf:resource="&owl;Thing"/>
 <rdfs:range rdf:resource="&iso15926-x;formula"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#is_mentioned_in"/>
</owl:ObjectProperty>
<!--

4.3.2.17 signal

An object is a signal if and only if:

it is an information_carrier;
it is a iso15926-2:stream.

NOTE OWL specification:

-->
<owl:Class rdf:about="&iso15926-x;signal">
 <owl:equivalentClass>
  <owl:Class>
   <owl:intersectionOf rdf:parseType="Collection">
    <owl:Class rdf:about="&iso15926-x;information_carrier"/>
    <owl:Class rdf:about="&iso15926-2;stream"/>
   </owl:intersectionOf>
  </owl:Class>
 </owl:equivalentClass>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#signal"/>
</owl:Class>
<!--

4.3.2.18 formula

An object is a formula if and only if:

it is one or more statements.

NOTE 1 The class formula is the same as the class http://www.w3.org/2000/10/swap/log#Formula defined within the Semantic Web Application Platform.

NOTE 2 OWL specification:

-->
<owl:Class rdf:about="&iso15926-x;formula">
 <owl:sameAs rdf:about="http://www.w3.org/2000/10/swap/log#Formula"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#formula"/>
</owl:Class>
<!--

4.3.2.19 creates_formula

An object is a creates_formula relationship if and only if:

it is a basics:mapping between iso15926-2:activity and formula;
the formula is created by the iso15926-2:activity.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;creates_formula">
 <rdfs:domain rdf:resource="&iso15926-2;activity"/>
 <rdfs:range rdf:resource="&iso15926-x;formula"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#creates_formula"/>
</owl:ObjectProperty>
<!--

4.3.2.20 formula_created_by

An object is a formula_created_by relationship if and only if:

it is the inverse of creates_formula.

NOTE OWL specification:

-->
<owl:ObjectProperty rdf:about="&iso15926-x;formula_created_by">
 <owl:inverseOf rdf:resource="&iso15926-x;creates_formula"/>
 <rdfs:isDefinedBy rdf:resource="&iso15926-x-doc;/information.htm#formula_created_by"/>
</owl:ObjectProperty>
<!--