requestSyncTime() node_handle, Arduino

Hi Does someone know what this line [link text](https://github.com/ros-drivers/rosserial/blob/40f61b98e6865ec4127d8949158ee607d62a3aaf/rosserial_client/src/ros_lib/ros/node_handle.h#L375) does? publish(TopicInfo::ID_TIME, &t); It is in `requestSync()` function. Also what is the purpose of the function `requestSync()`and `syncTime(uint8_t data)`? The first one publishes a message to the host, the second receives it? How does this happen in detail? Thanks