core + attic (Attic Area): these terms have been either depricated from the core or extentions, or removed from pending as not accepted into the full vocabulary.

numTracks

Canonical URL: http://schema.org/numTracks

Thing > Property > numTracks

The number of tracks in this album or playlist.

Usage: Between 10,000 and 50,000 domains
Values expected to be one of these types
Integer
Used on these types
MusicPlaylist

Schema Version 3.2