You can't integrate the XSD model precisely as it is defined because Wikidata doesn't allow all of the constraints that XSD allows. Specifically, you'll notice that you can't force an item to have a specific property (like the document or epigraphic reference in your model) and enumerations aren't currently supported. Wikidata has a global collection of properties and any item can use any arbitrary subset of them. The list is here:
. Some of the ones you want already exist, like material used for a building.
. I just added two statements (when you use a property, called a claim without references) to the Potaissa item that you use as an example.
> Date: Tue, 26 Mar 2013 22:50:52 +0200
> From: saturnian@gmx.com
> To: wikidata-l@lists.wikimedia.org
> Subject: [Wikidata-l] A data model for Roman forts (castra)
>
> Hi all,
>
> I recently attended "Wikidata meets archeology" symposium and I came
> across the question how a well structured and comprehensive data model
> of Roman forts (castra) could be integrated into Wikidata and then used
> on Wikipedia. For this I developed a raw XSD model based on the data
> model of Wikipedia's Infobox castrum. I put this model on the talk page
> of Q88205 (https://www.wikidata.org/wiki/Talk:Q88205) adding also a
> simple example. I would like to know this data model could be integrated
> into Wikidata? It is feasible? Is it too complex?
>
> Thank you,
> Saturnian
>
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