[ASHRAE Standard 62.1]: the air in an enclosed occupiable space.

[ASHRAE Standard 62.2]: air in an occupiable space.

[EN 16798-3:2017, 3]: air in the treated room or zone (IDA; colour Grey)

The main term is air while indoor is its attribute always spit from the main term by comma. The lines below report three different definitions according to the listed standard, respectively ASHRAE Standard 62.1, ASHRAE Standard 62.2 and EN 16798-3:2017, 3, where the number after comma is its reference number in the last standard.

To avoid duplications but maintain the highest degree of flexibility, some compound term (main pus attribute) are reported twice, but one of then refers to the other for the definition, giving the priority to the main term. The reference term is bracketed and appears below the term in regular font (no any definition is given there). For instance: