| 18506-6 | P wave axis horizontal plane Reference beat |
| 18507-4 | QRS axis.horizontal plane Reference beat |
| 18509-0 | T wave axis.horizontal plane Reference beat |
| 18511-6 | P wave onset Reference beat |
| 18512-4 | P wave offset Reference beat |
| 18513-2 | QRS onset Reference beat |
| 18514-0 | QRS offset Reference beat |
| 18515-7 | T wave offset Reference beat |
| 18516-5 | P wave axis frontal plane Reference beat |
| 18517-3 | QRS axis.frontal plane Reference beat |
| 18518-1 | T wave axis.frontal plane Reference beat |
| 18519-9 | Reference beat |