{
  "name": "line_substring",
  "type": "function",
  "description": "Returns the portion of a line (or curve) geometry which falls between the specified start and end distances (measured from the beginning of the line). Z and M values are linearly interpolated from existing values.",
  "arguments": [ {"arg":"geometry","description":"a linestring or curve geometry"},
                 {"arg":"start_distance","description":"distance to start of substring"},
                 {"arg":"end_distance","description":"distance to end of substring"}],
  "examples": [ { "expression":"geom_to_wkt(line_substring(geometry:=geom_from_wkt('LineString(0 0, 10 0)'),start_distance:=2,end_distance=6))", "returns":"'LineString (2 0,6 0)'"}]
}