I have different own POI databases that I like to merge with OSM data. I have converted my data to OSM XML files and megr them with osmosis. So far it works, but I wonder if there are any restrictions to the node ID number. Which number ranges are safe to use and will never have a conflict with extracts frm planet.osm file?

PS: the additional data I use are SRTM contours, geocache way-points and other location based POIs. I pack it into GPSmid on my phone.