If you add a 1 as last argument, the script will not terminate if moveline goes in an empty line.
You can also use it on findline and findinline
findline 1 1 or findinline 1 1 (you need two numbers here because they have an optional parameter)
If findinline fails, the pointer will jump to the end of the row.
Have a look at my discogs or AMG scripts as example.
And no, there is no futher documentation available at the moment.