Imports would fall into four classes.
1. Imports forbidden either (a) by legislative prohibition, or (b) by prohibitive taxation.
2. Imports admitted but taxed.
3. Free imports.
4. Imports encouraged by bounties.
Exports might be graded in similar fashion.
1. Prohibited exports (e.g., sheep and wool, raw hides, tanned leather, woollen yarn, textile implements,[12] certain forms of skilled labour).
2. Exports upon which duties are levied (e.g., coals[13]).
3. Free exports.
4. Exports encouraged by bounties, or by drawbacks.