[Player API] Start/Resume User playback parameters

[DavidNgHK]

I am working on create music player with Spotify as data source currently.

And when i reading the API for put tracks to player , i got confusing about body parameters

Below is my questions:

1. What is difference between context_uri and uris ? Look like uris is list of track uris and context_uri is album/playlist uri ?
2. What is maximum length of uris ?
3. What parameter offset meaning ? It meaning skip first X items in uris ? but how about context_uri ?
4. What parameter position_ms meaning ? It meaning skip X ms in first track ? what happen if given ms is more than first track ?