Options passed via GET:
p - new method <easting>|<northing>|<zoom level> eg http://openmaps.the-hug.net?p=547923|262865|8
Remember these are eastings and northings down to metres i.e. based on full OSGB XX 99999 99999 with the most significant digits being mapped from the XX code (see var osGrid in main.js or ./php/inc/osgrid_letters.inc for the mapping)
p - old method EEEEEENNNNNNZ, this is broken (doesn't work in the far north of Scotland where you get seven digit northings) so use the “|” instead for new sites. I'm retaining this in case there's anyone out there still using this option the old way.
lat / lon / name - center map at that location and put a marker on the map. Marker will be labelled with the name. This will be displayed “embedded” i.e. with no control options on the left and no ability to add waypoints or move the marker.
gpx - this has to be in the directory ./gpx but it can also be a URL of a GPX file if it's on the approved list of domains. Search for “^www.” in index.php to see the current list. If you want the GPX file to be displayed embedded also pass “embedded set to “Y”
kml - this has to be in the directory ./kml but as with GPX files it can also be a URL of a GPX file if it's on the approved list of domains. Search for “^www.” in index.php to see the current list. KML files are always displayed embedded. Our support for KML files is at the same time limited and extended - spec here.