Non-Reified Attributes
To create an attribute in the ontology, click "Add Attribute" in the Ontology Editor, and the following screen will appear:
Attribute names can be derived from three sources, as selected by clicking on the appropriate button at the top of the screen: (1a) User-input; (1b) based on an existing entity; or (1c) using a word/phrase from the current word list . In case (1b), which seldom arises, entities already existing in the ontology will appear in Area W, and one of these can be selected to be the name of an attribute. In case (1c), the current word list will appear in Area W. Selecting any word/phrase will place it in the "Attribute Name" box, and display the context(s) in which it is used in Area Z.
The above example shows the selection (2) of a new "Top Level Value Domain" for the attribute, and, by not placing a tick in the "Reify", signals that this will not be a reified attribute. (This procedure also applies to the creation of Free Text and Free Numeric domains.) Its name is then entered (4), together with a suitable name for its inverse (5). At this time, inverse attributes are only used by LegendBurster for "referring attributes" (discussed below). However, by including them in the ontology they enhance its understandability to other users. A comment describing the attribute is then entered (6), which will be visible whenever the attribute is referenced in other parts of LegendBurster.
An icon can then be assigned to the attribute. Icons have to be of the standard ".ico" format for icons in Windows programs. Careful design and choice of icons can substantially enhance the appearance of LegendBurster's semantic nets when they are presented in "TreeViews". They also facilitate faster interaction with the "TreeViews" by allowing users to recognise attributes by shape and colour, rather than by having to read words.
The attribute is then created by clicking on the "Create" button, which produces one further form before the activity can be completed - a form to establish which entities are to be qualified by the new attribute.
By default LegendBurster will assume that the attribute is to be linked to the top levels of the two semantic nets in which it will be used (mapObject descriptions, and query descriptions). These may need to be adjusted - as they would, for example, if the attribute just created had been "Element", which needed to be linked to "ElementAssemblage". In this case, the "mapObject" and "query" links would be turned off, and a link to "ElementAssemblage" turned on.
The link-type setting of "Primary and Inherited" relates to the visibility of "inherited attributes", which are discussed in the "Hetero-Inheritance" section of Appendix 1. Hetero-inheritance is not implemented in this version of LegendBurster. If you believe that you have an application that requires hetero-inheritance, please contact Georeference Online Ltd.
Clicking on "Create" ((8) in the diagram) will complete the creation of the Top-Level Value Domain attribute (or Free Text or Free Numeric attribute).
If the attribute was a new Top Level Value Domain Attribute, values will need to be entered to the domain, either manually, or by importing from a TreeList Editor file, as described in the "Values: Adding, Editing and Importing" section.
Reified Attributes
The procedure for Reified Attributes is as described above for non-reified attributes, except that, with the selection of checkbox (3) in the "Add Attribute" form, and entity with the same name as the attribute will be created - hence allowing it to have its own attributes, which will have to be created and linked to the entity
Creating attributes with Sub-Level Value Domains is as described above for Top Level Value Domains, with three exceptions:
(1) Reification
is not possible, and is disabled;
(2) A Top
Level Value Domain has to be chosen ((3) in the diagram below) from which
the sub-domain will be derived;
(3) Instead
of adding values to an initially empty Top Level Value Domain, values
have to be selected for inclusion in, or exclusion from,
the Sub-Domain, based on check-boxes that are displayed when the Sub-Domain's
values are "edited". (This
"editing" is restricted to setting the include/exclude parameter,
and to inputting a comment which may be different from the comment attached
to the value of the Top Level Domain).
Thus, to create an attribute with values in a sub-domain , click "Add Attribute" in the Ontology Editor, and the following screen will appear:
After choosing a name for the attribute ((1) and (4) in the diagram, - alternatives described above) and its inverse (5), add any desired comment (6).
Then select "New Sub-Level" ((2) in the diagram), and chose a target domain from the available domains displayed in Area (X). By default, all values in the Top Level Domain will be included in the sub-domain - thus requiring that values to be excluded from the sub-domain will have to be identified using the "Edit Values" procedure. If it is likely to be more convenient to identify only the values that are to be included in the sub-domain, then the tick should be removed from the box labelled "Include all values from value domain", at the bottom of Area X.
Assign an icon to the attribute if desired (7), and click on "Create". (See notes above on the importance of icons, and on the linking of the new attribute to the correct entities.)
Once the sub-domain attribute has been created, select the attribute in the "Attributes" column of the Ontology Editor, and use the "Edit Values" procedure to set which values should be included, and which excluded.
"Referring" Attributes take as their value some other kind of entity, and they are described in the section entitled "Representing Complex Entity-Attribute-Value Associations" in Appendix 1.
To create an attribute in the ontology, click "Add Attribute" in the Ontology Editor, and the following screen will appear:
Choosing the name ((4) in the diagram) for the referring attribute is the first necessary action, and should be done together with careful attention to the name that will be given to the inverse attribute ((5) in the diagram). This is because the inverse attribute will become an attribute of any target entity of the attribute being defined. (For Example: If "vegetation class" has the referring attribute "OccursIn", its target class is a "climate zone", and its inverse is "Hosts", then the entity "climate zone" will get a "primary" attribute called "Hosts", which has the target class "climate zone".)
Attribute names can be chosen according to any of the methods described in Section (a) above. Any comment ((6) in diagram) entered at this stage will be associated with both the attribute and its inverse - although the comments for each of them can be individually edited from the Ontology Editor screen once they have been created. The Entity (or entities) which the attribute will refer "From" are selected in Area X, and the target entity (or entities) are selected in Area Y.
Assign an icon to the attribute if desired (7), and click on "Create". (No opportunity is offered at this stage to assign an icon to the inverse attribute - although this can, and should, be done from the Ontology Editor, once the inverse attribute is created. (See notes above on the importance of icons.)
Clicking on "Create" will complete the creation of the Referring Attribute and its inverse.
When a link is to be established between two already existing entities using an already existing referring attribute, the entity selected in the Ontology Editor "Entities" column will be considered the source entity, and the system will prompt the user for the target entity, as illustrated below:
The target entity or entities are simply checked in the available check-boxes, and the "continue" button is clicked.
Careful attention must be paid to the semantic correctness of any such links created.
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IMPORTANT NOTE: Attributes should not be removed from the ontology if they are present in any of the mapObject descriptions or queries in the LegendBurster project. They can, however, be added at any time during the life of a project. |
Simply select the attribute in the "Attributes" column of the Ontology Editor, and click on the "Remove" button.
Top Level Value Domain Attributes may not be removed from an ontology until all their sub-domains have been removed.
Thereafter, simply select the attribute in the "Attributes" column of the Ontology Editor, and click on the "Remove" button.
Simply select the attribute in the "Attributes" column of the Ontology Editor, and click on the "Remove" button.
Selecting a Referring Attribute for removal causes LegendBurster to produce a form showing all the links that the Referring Attribute can participate in. Individual links may be selected for removal. If all links are selected, the attribute, and its inverse, will disappear from the Ontology Editor.
Remember not to remove links that have already been used to describe existing mapObjects.