Listed by a Tralbum, in the release's order.
index: number
The track's position in the release's list. The player keeps it, with the page URL, to resolve the track again once its stream URL expires.
optional
trackNum: number
title: string
optional
duration: number
In seconds, with a fraction.
streamUrl: string | null
A signed URL that expires. Null when the track can't be played.
streamable: boolean
False for preorder, unreleased and still-encoding tracks. They stay in the list so that the numbering matches the release, but the player skips them.
capped: boolean
Set when Bandcamp capped its free plays, so it may serve only a clip.