CAD tip # 5384:

Blocks can be optionally rotated to tangent direction at each vertex. You can optionally insert blocks also to the midpoints of arc segments. You can also insert aligned block just at line endpoints (the ENDBLK command).

Such blocks can be then used e.g. for vertex coordinates lists of your polylines to a TXT or XLS file - just create a schedule of the inserted vertex-blocks (EATTEXT, ATTEXT, DATAEXTRACTION or Excellink).