What operating system are you using? What version of the software?

Essentially the directions are a text file of the form where the first line is the number of directions and the remaining lines specify the vectors. See the Manual on page 205.

https://medicine.yale.edu/bioimaging/sui...

10

1. 0.0 0.0

1. 1.0 0.0

1. 0.0 1.0
...