Infill Type

Migrating: For MatterControl 2.0 the MatterControl documentation is moving to matterhackers.com/mattercontrol/support/. 
Function
The geometric shape of the support structure for the inside of parts.
Parameters
Available as presets only:
 GRID
 TRIANGLES
 HEXAGON
 LINES
 CONCENTRIC
Example(s)
GRID
A series of parallel lines in one direction and a series of perpendicular lines, all on the same layer.
TRIANGLES
A series of equilateral triangles.
HEXAGON
A series of equilateral sixsided shapes, like a honeycomb.
LINES
A series of parallel lines in one direction on one layer, then a series of perpendicular lines on alternating layers.
CONCENTRIC
A pattern of denoting circles, arcs, or other shapes that share the same center, the larger often completely surrounding the smaller.^{[1]} In this case, the shapes take on the shape of the model, a square.
References
 ↑ Oxford Advanced Learner's Dictionary, US English.