There is a Java enum PointType that contains the types you can annotate an point with.
/** Before a type is determined */
UNKNOWN,
/** If the point has a sharp angle for now 30 degrees is set as the limit */
HARD_CORNER,
/** If it is not a hard point */
SOFT_POINT,
/** 3 or more lines meets, U is for unknown */
U_JUNCTION,
/** 3 lines meet 2 are collinear and the last is somewhat orthogonal */
T_JUNCTION,
/** 3 lines meet less than 180 degrees between all of them */
ARROW_JUNCTION,
/** 3 lines meet, not a T junction */
Y_JUNCTION,
/** point is an end point,
* maybe later there should be a distinction between end points and have
* nothing else close by and end points that have close neighbors */
END_POINT,