What is Sprite.Create 5th parameter?

I use some tilemap asset(Bitbucket)

When make Tile object there is some code make sprite

TileSprite = Sprite.Create(TileSet.Texture, Source, Vector2.zero, TileSet.TileWidth, (uint)(TileSet.Spacing * 2));

this code use five parameters. But as I know Sprite.Create use 4 parameter.(Unity - Scripting API: Sprite.Create)

What is identity of 5th parameter?

My Visual Studio says its a “extrude” value of type “uint”. Documentation of Unity 4.3 says only :

Extrude Edges property added to Advanced mode. It can be used to extrude the internal sprite mesh edges if needed for custom texture-space effects.

Sprite Create can have up to 7 parameters (check all overloaded methods).

Edit//
Unity have another description for that:

How much empty area to leave around the sprite in the generated mesh.