There are 6 different strands in each chute.
Strands in Floors
Each rectangle represents a boxrow that belongs to the floor. There are 3 cells in each boxrow. For the purpose of determining the strand, the exact position of the digit in that boxrow is ignored, as long as it is placed somewhere in that boxrow.
When we ignore wrapping around, each strand follows a diagonal path. Strands that follow a \ direction are identified with the letter N and strands in the / direction are identified with the letter Z. The number refers to the starting position, which can be 1 (top), 2 (middle) or 3 (bottom).
Strands in Towers
In towers, the strands are numbered from left to right.