Found that it is ompossible to put private marker - marker visible only for player. Even marker placed in Direct Channel is visible to person standing near you.

Here is a feature request:

1. Add new channel (customizable?) that will give ability to put private markers or that may be configured to do that (channel with settings - distance of marker sync)

2. Add individual maps for hardcore players. Every player has it is own map. Markers placed on map will not sync between maps. Another player can take your map and see all your markers.