They are not normal two-number coordinates. Also, HWK Michael told me that the ONLY to do blocking is to type the coordinates manually. Have you ever successfully added blocking with "export string"?
No I haven't needed to as of yet, but I don't see why there would be a problem using the export string, the exported string appears to be the correct format (starts with the number count e.g. how many coordinates) and then it lists all the coordinates.
Perhaps the generated string needs to be modified in some way, but I don't believe you would need to manually type them out, hopefully he can answer when he comes on next.