====== Product modeling ======
Product modeling is the process of expressing information about an **individual** product and should be done conform a sound methodology. The term 'product' in this context is used in its widest sense and is thus equivalent to the term 'physical object'. The result of product modeling will be a collection of expressions about one or more 'products', ranging from simple components to complicated assemblies and systems and facilities. When a collection of expressions is about one product, we call it a **product model**. A product model can be a model of any man made object or natural object. A product model can be a stand-alone model, it can be an element of a model library, or it can an integral part of a [wiki:"Facility Information Models" Integrated Information Model]. Product modeling differs from [wiki:"Knowledge modeling in Gellish" knowledge modeling] which aims at expressing knowledge about **kinds** of things.
 
====== 1. Real products and imaginary products (designs) ======
A product information can either be information about a real world object or it can be about a design (a realistic imaginary individual object). A design typically expresses information that is a 'product of the mind' and is intended as requirements for the fabrication and assembly of one or more real things. Such a specification of an imaginary thing necessarily has aspects (properties and qualities) that are deemed characteristics of the imaginary product. On the other hand the real individual things will have aspects that are observed or measured. The Gellish methodology recommends that designs and real world products are distinguished as different products, each with its own characteristics. When a product is fabricated and assembled according to a design it becomes a (materialized, realized) real physical object, that has characteristics that can be measured and which should be compliant with the characteristics of the design. Knowledge about kinds of things is valid for the real things as well as for the imaginary things, as long as the imaginary things are realistic. Examples of product models are: modeled designs or models of real facilities, pieces of equipment, motors, cars, etc. or one of their components, such as bolts, shafts, cables, etc. Bigger assemblies, such as a buildings, railways, factories or process plants are products as well.
Real things and imaginary things are related by a materialization relation as follows:
^Name of left hand object^Name of kind of relation^Name of right hand object^
|X-123.456|is a materialization of|P-1201|
|X-123.456|is classified as a|BINGHAM model 2X6A VCM|
|P-1201|is classified as a|multi stage deepwell pump|
|P-1201BINGHAM model 2X6A VCM|is a model of|multi stage deepwell pump|
The above expression specifies that X-123.456, being an equipment registration number, is a real world object that is derived from and should be compliant with the design object ('tagged item') P-1201. Because both objects have different identities (UIDs), they are both classified. Those classifications may be different, but should be consistent as in the example above, where the real object is classified by a manufacturer's 'model and size' which is a model (subtype) of the classifier for P-1201 as is specified on the fourth line. 

A design process for a product results in a product specification or product model that will be the performer or enabler of a process (the function of the product). Or more precise: a design is a product model that specifies the composition and characteristics of a realistic imaginary individual physical object that is intended to be realized by a materialized physical object and that is suitable to perform the required function. \\

====== 2. Definition of a function ======

The design of a product often begins with a functional design. Therefore, we will first discuss the definition and the modeling of functions.\\
A design process usually begins with a functional specification or the requirements, for example as specified in the 'Systems Engineering' methodology (see ISO/IEC 15288). \\
Such a functional design specifies a 'function' that shall be performed by a new facility or product. The intention of a specification of the function is that the options for a technical solution are kept open. The idea is that in a later stage it shall be specified what the characteristics are of the designed physical object that will performs that function. \\
If we want to model a design in Gellish we should be clear about what a function is and how we can distinguish between a design and a realized physical object.

A function as used in Systems Engineering appears to be a process that needs to be performed or enabled.

====== 3. How to specify a required function ======
The above definition of a function implies that a specification of a function in Gellish should start with the definition of the process that needs to be performed. So design of a function means: design of a process (an occurrence). For example, there may be a requirement to clean waste water, which in other words can be expressed as the requirement that we need the function 'waste water cleaning', or we may require to transport a number of people. Such a required process is not a process in general, but a particular process with specified input and specified output, by which the required performance of the process is defined. For example, it is required to clean a particular stream of waste water, coming from a particular source, such as the effluent water of a particular plant. That particular waste water stream should have specified properties, whereas the cleaning process will result in a clean water product stream that shall also have specified properties. The quantity and properties of those streams are not properties of the process, as is often specified, but they are properties of the streams that specify the required performance of this particular water cleaning process.

A required function or process can be specified in Gellish as follows:

^UID of left hand object^Name of left hand object^UID of an idea^UID of kind of relation^Name of kind of relation^UID of right hand object^Name of right hand object^UID of unit of measure^Name of unit of measure^
| 101 | cleaning process-1 | 201 | 1225 | is classified as a | 192452 | water treatment |   
| 102 | S1 | 202 | 1225 | is classified as a | 105 | waste water stream |   
| 102 | S1 | 203 | 4785 | is input in | 101 | cleaning process-1 |   
| 103 | S2 | 204 | 1225 | is classified as a | 106 | clean water stream |   
| 103 | S2 | 205 | 4786 | is output of | 101 | cleaning process-1 |   
| 102 | S1 | 206 | 1727 | has as aspect | 104 | quantity of S1 |   
| 104 | quantity of S1 | 207 | 1225 | is classified as a | 551327 | volume flow rate |   
| 104 | quantity of S1 | 208 | 5025 | has on scale a value equal to | 920466 | 300 | 570450 | m3/d|
|   | etc. |   |   |   |   |   |   |
Note that UIDs above 1000 are selected from the [[:Gellish English Dictionary|Gellish Dictionary]]. Lower numbers in this example are user created. The objects 101 through 104 are individual objects that are properly defined by the facts that classify them by a concept (or kind) from the Gellish dictionary. However, the concepts with the UIDs 105 and 106, waste water stream and clean water stream, do not exist yet in that dictionary. Therefore they should be defined according to the [[:proper definition of a concept|rules for proper definitions of concepts]] and by doing so they become proprietary extensions of the dictionary. The process can be specified in more detail as is described in the section about [[:Modeling of activities and processes|modeling of activities and processes]].

====== 4. How to specify product information ======

Product information or a product model of a real or imagined (designed) individual product consists of a coherent collection of expressions of ideas about the product. Typically it has a hierarchy of decompositions of the object as its main structure, expressed as a collection of composition relations. Each component in the model has its own aspects. Documents and drawings may be related to the whole assembly or to the components that they describe. For example, a product model can be as complex as a model of a complete process plant, or of a facility such as a railway system and its components, but it can also be a single device or a simple component. \\
A product model shall at least consist of a classification relation and may include expressions that use the following kinds of relations:
  * Classification relations: Each assembly or component is an individual physical object that shall be classified by a concept that is selected from the Gellish English Database, or that shall be added as a proprietary extension according to the [[proper_definition_of_a_concept|rules for proper definitions of concepts]].
  * Composition relations: Every component of a designed assembly shall be specified as being a part of a larger assembly.
  * Possession of aspect relations: The aspects (characteristics, properties and qualities) of the assemblies and components shall be defined and each aspect shall be qualified or quantified (possibly on a scale), whereas the qualitative aspects shall also be selected from the Gellish Dictionary or from a proprietary extension of it.
  * Involvement relations: The assembly and/or its components can be related to processes or activities in which they participate, either as performer or in another role.
  * [[http://wiki.gellish.net/document_management|Presentation relations]]: Each object can be related to a document in which it is described and that is the content of a file that is stored at some address on a device or is included as a hard copy in a physical document, such as a binder.

An illustration of the application of a some of the above relations for the design of process unit 100 is given in the following table:
^Name of left hand object^Name of kind of relation^Name of right hand object^
|process unit 100 |is classified as a |water treatment unit|
|process unit 100 |is performer of |cleaning process-1|
|V-101 |is classified as a |horizontal vessel|
|V-101 |is a part of |process unit 100|
|V-101 |has as aspect |internal volume of V-101|
|etc.| | |

An extensive description of the design of objects is provided in [[http://www.lulu.com/shop/andries-van-renssen/semantic-information-modeling-methodology/paperback/product-22457361.html|'Semantic Information Modeling Methodology Application Handbook']] that is available via the download area of this website.

A specification of a process or a specification of a design can be done from scratch, as in the above example, but it is also possible first to express [[:Knowledge modeling in Gellish|knowledge in Gellish]] about a process and/or a performer or enabler of such a kind and then use that knowledge in knowledge-based design software for guiding the development of the specification of the process and/or of the design.

**//Continue with//** [[:Modeling of activities and processes]]