I wondered if adding extend statements in-line with data would offer a solution, or at least some insight.

If so I have not found it yet.  Interested to see if anyone else can:

1. Make the loop generate anticlockwise and produce a gap at station 2, with the second instance of 2 on the right of the first instance.
2. Produce a gap at station 7.

Here is my first attempt.

extend start

extend right

1   2 1    0   -10

2   3 1    0   -10

3   4 1    45  -10

4   5 1    45  -10

5   6 1    45  -10

6   7 1    90  -10

extend left

7   8 1.71 225  60

8   9 1    225  10

9  10 1    225  10

# extend ignore

10  2 1.8  225 -32.2

extend right

7  11 1    90  -10

ie this traverses 1 2 10 9 8 7 then backwards through 6 5 4 3 2, then 7 to 11

Not at all the sequence the data is presented in the data table above

The ignore statement before leg 2 10 is ‘ignored’ if it is uncommented.

START 1@extendedloop

RIGHT 2@extendedloop

RIGHT 10@extendedloop

RIGHT 9@extendedloop

RIGHT 8@extendedloop

RIGHT 7@extendedloop

LEFT 6@extendedloop

LEFT 5@extendedloop

LEFT 4@extendedloop

LEFT 3@extendedloop

LEFT 2@extendedloop #now back to 7

BACK 4@extendedloop

BACK 5@extendedloop

BACK 6@extendedloop

BACK 7@extendedloop

RIGHT 11@extendedloop # and 7 to 11

Done

Bruce