start/stop method for OscillatorNode

The idl for the start and stop methods for the OscillatorNode both take a
required when argument. But the description of the methods says they are
the same as AudioBufferSourceNode.  But the AudioBufferSourceNode does not
require a when argument.

So, what is the actual behavior of start and stop for OscillatorNode?

Perhaps it's also a bit confusing since start can take several arguments in
an AudioBufferSourceNode, but can't in an OscillatorNode. The idl makes it
clear, but the text description doesn't point out this difference.

Ray