Pipe attachment problems

[frikandel345]

I am currently building a mod which is an extension to the current oil production chain. I am stuck while creating my first entity. It has to become an entity of 5x7 blocks, with 2 inputs, and 6 outputs.

I can't figure out how the input and output of chemical plants and oil refineries is described. I have found how it is done in the base game but there it gives the following script (chemical plant):

fluid_boxes =
{
{
production_type = "input",
pipe_covers = pipecoverspictures(),
base_area = 10,
base_level = -1,
pipe_connections = {{ type="input", position = {-1, -2} }}
},
{
production_type = "input",
pipe_covers = pipecoverspictures(),
base_area = 10,
base_level = -1,
pipe_connections = {{ type="input", position = {1, -2} }}
},
{
production_type = "output",
pipe_covers = pipecoverspictures(),
base_level = 1,
pipe_connections = {{ position = {-1, 2} }}
},
{
production_type = "output",
pipe_covers = pipecoverspictures(),
base_level = 1,
pipe_connections = {{ position = {1, 2} }}
}
}

I have the following questions concerning this script:

Why do the pipe_connections go from -2 to 2, if the entity only consists of 3 blocks?

What does base_level mean/do?

What does base_area mean/do?

How does the grid of pipe_connections work?


I hope someone can help me with this