Within a data domain, data can be arranged hierarchically as assemblies, subassemblies, attributes, and properties. Each assembly can have zero or more attributes and zero or more subassemblies, and each attribute can have zero or more properties. Subassemblies can have subassemblies. You can think of assemblies and subassemblies as branches in a tree, and attributes as the leaves. Here is an example of what a tree might look like:

Data Domain
    Assembly
        Subassembly (zero or more)
            Attribute  (zero or more)
                Property  (zero or more)
        Attribute...
        Attribute...
        Attribute...
            Property...
            Property...
            Property...
        Subassembly
            Subassembly
                Attribute...
                  Property...
                  Property...
            Attribute...
            Attribute...
                Property...
    Assembly...

and so on.

The written syntax for all of these levels uses a dot (.) to divide the names, rather than a colon that was used for the data domain name. Hence, the syntax of point in a property in an attribute in a subassembly in an assembly in a data domain would be:

domain:assembly.subassembly.attribute.property

Properties describe the attributes in more detail. An attribute can have a default property such that if you interact with the attribute point directly you will in fact be interacting with its default property. For example, an item might be plant.temperature, with properties value, highlimit, units. This would create 4 tags:

The tags:

are aliases of one another. Both refer to the default property of plant.temperature. If you specify no property at all for an item, the item takes on the default property.