Learning about Cut-back in tapestry

As I mentioned in my previous post, I saw the technique of using slits in the weaving to enhance the design. 

I have also just learnt about a similar technique, cut-back, in my historic piece, where you pull hard on the weft where the hatching meets, causing a small hole to appear.  I have not got this technique to work all that well yet as I have only used it near an edge and I was nervous about pulling too tightly and causing the side to pull in.  But this technique also gives a design element by making a space in the weaving.

As you can see, it is a subtle technique.  I have not done much here and will try to post a clearer picture when I have tried the technique again later in the work. (This is the same piece of weaving, taken with different settings on my camera, hence the different colours.)