To automate connection of routing elements to each other you may use connection points - connectors. They represent LCS, which have certain types.
If the LCS type does not exist in the used hierarchy of types, next to the LCS there will be "from document" note.
When you create connectors, for their positioning you may use only objects with compatible type, or objects with no type assigned. When typed element is added to a model, system checks whether a given connection point may be used for connecting element, i.e. checks objects for compatibility.
For more information about creating connectors refer to chapter "Local Coordinate Systems".