The sync and nosync flags indicate whether or not a looping command is synchronized to the universe clock. This is useful if several commands need to be synchronized with each other, or a slow moving object needs to be seen in or near the same position by all users.
In most cases the "nosync" flag will be desirable with commands linked to the activate trigger. This is because synchronized movements start from a pre-calculated position based on universe time.
See the individual commands such as move and rotate for defaults or other additional information.
activate rotate 0 0 20 nosync
create move -1 0 0 sync time=5 wait=3