Especially in small scale scenarios or viscous liquids the formation of thin liquid sheets (very thin layers of liquid) are very common and pose a difficult problem. Effex has a particle based state-of-the-art thin sheet algorithm that uses anisotropic and particle density information to close holes in a liquid simulation in a physically based manner.

That's why the following nodes are required to be available in the scene:
Volume Properties (calculating at least density...anisotropy can be calculated by the thin sheet itself)

It's purpose is to avoid simulating liquids at higher resolution just to preserve thin sheets. Instead you save simulation time by using the thin sheet operator. The thin sheet performance is highly dependant on the particle count and can get quite slow (it's a complex algorithm really).

The default settings provide a robust ground truth for thin sheets.