Table 1. The alveolar type classification based on the mass encapsulation (non-filled or filled) and LIV appearance (tessellated or non-tessellated). The table also defines the abbreviations for each type.

		LIV appearance of epithelium
		Non-tessellated	Tessellated
Mass	Non-filled	T0F0	T1F0
encapsulation	Filled	T0F1	T1F1