Minecraft wiki entry for Model, associated text: While the first model, the fence post, is always used, the other models are used only if certain conditions are met. Here the sides of the fence are applied only if there is another adjacent block next to this one. As there is just one model for the post and another one for all the sides of the fence, which then is rotated by increments of 90 degrees, the amount of models needed for all the different possible set-ups of fences can be reduced to two. Compared to the five models and 16 variants used in Java Edition 1.8, this is a rather big improvement. This tool helps to edit JSON data JSON Parser and you can also use Json validator.