Introduce a new FixingsFacet to add save access to the current Km Values which are accessed by a String like a map must be checked for null. The new FixingsFacet adds a getCurrentKm method that abstracts the direct access to the CallContext and always returns a valid double value.

SYMBOLSET
SYMBOL
  NAME 'point'
  TYPE ELLIPSE
  POINTS
    1 1
  END
  FILLED TRUE
END
SYMBOL
  NAME "square"
  TYPE VECTOR
  POINTS
    0 0
    0 1
    1 1
    1 0
    0 0
  END
  FILLED TRUE
END
END