December 2014

Every OCHRE project has its own project Taxonomy which represents and organizes the project's vocabulary for describing its data. Since many projects have similar needs, OCHRE allows the taxonomy, or portions thereof, to be shared among projects.But since projects also often have their own very specific needs, a taxonomy can also be customized.

Take a look at a portion of the Taxonomy of the OCHRE Tutorial. Notice that it is organized as a hierarchy (no surprise!) where higher-level items constrain the items contained within them. This is a very concise and efficient representation. Since it is a hierarchy you already know how to insert and delete items to build a branch of the taxonomy; it works just the same way as other OCHRE hierarchies.

TUT, taxonomy.JPG

Variables and Values

The difference between other hierarchies and the Taxonomy is that the elements of the taxonomic hierarchy are alternating sets of Variables (shown with a tag icon) and Values (indicated by the diamond icon).
  • Items shown in black are native to the current project.
  • Items shown in gray are borrowed from some other project but they can be used in other arrangements in the current project.
  • Items shown in red are "bound copies" that are borrowed in from another project in such a way that they cannot be changed here.

Note, especially that variables can be repeated at different levels of the hierarchy to indicate an increasing degree of specificity. For example, under Location or object type > Faunal remains we show the Faunal taxon variable which, at its highest level, lists a variety of high-level taxa including Amphibian, Bird, etc. But as we drill down the hierarchy, under Bird for example, we repeat the Faunal taxon variable to list specific examples of birds whose bones we might find on an archaeological excavation.

To repeat an item within a taxonomy, select the item to be repeated and use the Edit menu from the main OCHRE menu to Copy (Repeat) item. Navigate to the context in the taxonomy within which you want the item to be repeated, then select Edit, Paste item. This will insert a new instance of the same item within the selected context. It is important to understand that this is not a copy of the item; it is another instance of the same item. You can further edit either instance of the item and changes will be reflected by all instances of the item.
TUT, edit, repeat.JPG

Here we have repeated the Geographic unit variable within Landmark to allow us to further distinguish cultural vs. natural landmarks.
TUT, recursive variable.JPG
Variable used recursively

The Contexts tab of the item's edit pane (in the center) will show ALL hierarchical contexts in which an item is used. If you select the Geographic unit variable (any instance of it!) in the navigation pane, you will see all of its contexts listed.
TUT, variable contexts.JPG

The variables and values used within a project hierarchy that are custom to the project are also collected in their own Categories, Property Variables and Property Values, respectively. This simply allows a project to organize these items and have a convenient means to list them all, apart from the hierarchical, taxonomic context in which they are used.
TUT, property inboxes.JPG

Your turn

Let's have you add some additional values to the Geographic unit variable which will give us more options for describing Locations & objects.
  • Select the top-most Geographic unit in the navigation pane as the parent item under which you will add new items.
  • Use the insert-below button (if needed, see Inserting and Deleting Items) to add City, State, Body of water, or whatever entries you like.
  • Navigate to Landmark > Cultural landmark. Insert a new item; a Variable item will be inserted since the parent item, Cultural landmark, is a Value. Call the new variable Landmark type, or something similar if a variable by that name already exists.
  • Notice the different types of variables that can be created. Give this new variable the nominal type. This will let you create a restricted list of named values to be allowed for this variable.
  • TUT, variable type.JPG
  • Let's create some of those values. With the new variable still selected, insert a new item below. This time a Value will be generated since the parent item is a Variable. Call this value Church.
  • Re-select the new variable (Landmark type or equivalent) and add another value called Mosque. You have now defined Church and Mosque as the only two valid values of the variable Landmark type.
  • TUT, landmarks.JPG

You can imagine how other such lists might be created and extended, serving to provide valid values and using hierarchical nesting to enforce dependencies.

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