Tier
A group of tokens of the same type and purpose, usually sharing a similar schema. Each group is expected to exist conceptually adjacent to another tier where one tier depends on values from another tier.
Typically, there are three tiers of tokens:
The relationships between the tiers, values, and their final placement tend to be displayed in the following flow:
value ➜ primitive ➜ semantic ➜ component ➜ property
Where a permanent value is ultimately meant to be assigned to the stylistic property of an element. Tokens are used to abstract this in a way to allow for new values to be introduced without visiting the property directly making a very flexible system of presentation.