totalJobOpenings

This term is proposed for full integration into Schema.org, pending implementation feedback and adoption from applications and websites.

Thing > Property > totalJobOpenings

The number of positions open for this job posting. Use a positive integer. Do not use if the number of positions is unclear or not known.
Values expected to be one of these types
Integer
Used on these types
JobPosting

Source

https://github.com/schemaorg/schemaorg/issues/2329