Invisible Node

[X17]

My mod wall adds a wall node that can use for game borders. I want that it is invisible, but when I use a empty picture, the node will be black.
How I can make an invisible node?
And I want that no player can dig it. That funktioned, but it can destroyed by TNT.
What can I do that it can't destroyed by TNT?

X17

[Nathan.S]

Use an transparent texture, and set the correct alpha option in the node def for the block to be invisible. To prevent it from being exploded check out the on_blast callback.

[X17]

what is the correct alpha option?

[v-rob]

I would suggest that you add drawtype = "airlike" in your node definition, which will render your node invisible, no need for extra textures. To stop TNT from blowing it up, use on_blast = function() end, which should stop the majority of TNT mods.