The six channels — an introduction liù jīng biàn zhèng · 六经辨证入门

The six-channel framework from the Shanghan Lun sorts illness into six stages: Taiyang, Yangming, Shaoyang, Taiyin, Shaoyin and Jueyin. Taiyang is the exterior and the earliest stage, Yangming is interior heat, and Shaoyang is the half-exterior half-interior stage between them.

Its importance is historical as much as clinical. It is the earliest systematic attempt in Chinese medicine to describe illness as a process that moves over time, rather than a fixed label, and modern discussion of cold damage still uses its vocabulary.