Since the ItemAvailability seems to deal primarily with physical objects, I wanted to make sure that OnlineOnly could be applied to digital downloads. Or, should digital downloads not have an ItemAvailability?
Should the availability of digital purchases be marked as OnlineOnly?
ecommerce;schema.org;download
I think its not relevant if its a physical item or a digital item. An example that makes clear that the difference shouldnt matter when deciding if and how availability should be used: You could sell concert tickets, from your online shop and from your retail store, in digital form and in paper form (from both places).OnlineOnly means that the item can only be purchased from the web shop, while InStoreOnly is for the opposite case. Both can be used for digital and/or physical items. (I guess they are intended for cases where an organization has both, a web shop and a physical store, but using them in cases where only one is available shouldnt hurt.)If you want to convey that its a digital item (for download), you could use the availableDeliveryMethod property with the value http://purl.org/goodrelations/v1#DeliveryModeDirectDownloadSo for a product that can be downloaded after purchase from your web shop, it could look like:<div vocab=http://schema.org/ typeof=Offer>  <link property=availability href=http://schema.org/InStock />  <link property=availability href=http://schema.org/OnlineOnly />  <link property=availableDeliveryMethod href=http://purl.org/goodrelations/v1#DeliveryModeDirectDownload /></div>