Nesting HTML elements doesn’t affect Microdata unless you are using itemprop
.
Here you have two Microdata items, not related in any way:
<div itemscope itemtype="http://example.com/Example">
<span itemscope itemtype="http://example.com/Example">
</span>
</div>
Here you have two Microdata items, connected via the example
property:
<div itemscope itemtype="http://example.com/Example">
<span itemprop="example" itemscope itemtype="http://example.com/Example">
</span>
</div>
So you have to find suitable properties in Schema.org to connect items. For example, author
to connect a Book
to a Person
.
In your case:
The Intangible
type (which, by the way, doesn’t seem to be appropriate for substances) doesn’t provide a property that takes a PropertyValueSpecification
item as value. I don’t think that PropertyValueSpecification
is a suitable type anyway. Instead, PropertyValue
seems to be appropriate, which can be added (for example) to a Product
via the additionalProperty
property. Now the question is if it makes sense to represent your substances as products.
You might find more suitable types in the health-lifesci extension. For example, they define the Substance
type:
Any matter of defined composition that has discrete existence, whose origin may be biological, mineral or chemical.
But it has a medical background, and it seems to miss a way to add a PropertyValue
(or similar) item. If you think Product
can be appropriate, you could use both types together:
<article itemscope itemtype="http://schema.org/Substance http://schema.org/Product">
<div itemprop="additionalProperty" itemtype="http://schema.org/PropertyValue">
<!-- … -->
</div>
</article>
Schema.org is not intended to go into detail for all possible domains, so you might want to consider to find a domain-specific vocabulary/ontology.
As scientific domains like chemistry are typically strong in the Linked Data world, you might also want to consider to use RDFa instead of Microdata. The example from above could be marked up as:
<article typeof="schema:Substance schema:Product">
<div property="schema:additionalProperty" typeof="schema:PropertyValue">
<!-- … -->
</div>
</article>