Looking at ship traffic off LA/LB and noticed some ship’s status is given as “Stopped” or “Drifting” From a Marine Traffic website:
Stopped : Get notified when a vessel, that was previously moving , reports speed equal to or lower than 0.5 knots . This notification will remain inactive while the subject vessel is in a port or an anchorage.
Drifting : This notification updates you when our system detects that your selected vessel is drifting based on her transmitted speed and heading.
This article Not Under Command by Cambridge University Press: recommends that stopped be added as a Navigation Status option.