Google’s John Mueller has revealed that the search engine may support additional structured data types depending on how many websites are using it.
When Google thinks about what type of structured data to support next, it looks to see how many sites are actually using it.
If an unsupported structured data type is widely implemented then Google may decide to support it in search results.
Conversely, if Google sees no one is using a particular type of structured data, then it will likely not be considered any further.
This topic came up in a recent Google Webmaster Central hangout where the following question was asked:
“Is the item type ‘service’ supported by Google for reviews and ratings? The review guidelines mention services, but the supported item types doesn’t include services.”
In response, Mueller confirmed that Google’s developer site is the authority on supported item types.
The developer site is continuously updated, so if it says a structured data element is supported or not supported then that information is accurate.
With that said, site owners shouldn’t avoid using particular types of structured data just because they’re not officially supported.
If Google sees that sites are adopting an unsupported structured data type then that may influence Google’s decision to support it in the future.
You can hear the full question and answer in the video below (starting at 45:30):
“I realize we support a lot of different types of structured data, and sometimes it’s tricky to figure out which types apply to your particular case. But, in general, we try to be as explicit as possible in those guidelines with regards to what we support.
That doesn’t mean you shouldn’t use anything that we don’t support. It’s always a bit of a chicken and egg problem in that if we think about the next type of structured data that we do want to support, and we see nobody’s actually using it like that online, then perhaps we’ll try to find something else.
So if you feel like you really need to use this particular type of structured data for your specific use case, then by all means use that even if we don’t actually use it directly as a visible element in the search results.”