Why a folder is not the switch
A folder is a place, and a place is not a claim. The matter is the claim, and the claim is read.
The failure at this step
A page links a draft. The link check refuses, and the refusal names the draft.
A draft is a page that is written down as not built. The switch is in the matter, and the matter is why the draft is a decision rather than a folder.
About 1 min of reading
Take a draft out of the set
Write the switch
Before you run it, say out loud what it will print. Then open the answer.
Shrink the set
Before you run it, say out loud what it will print. Then open the answer.
Refuse a link to a draft
Before you run it, say out loud what it will print. Then open the answer.
A folder is a place, and a place is not a claim. The matter is the claim, and the claim is read.
A page links a draft. The link check refuses, and the refusal names the draft.
One name with one value. A name in the matter is a name a writer can set without moving a file.
The built set is what links are checked against. A draft out of the set is a draft that no link may point at.
Drafts are a number in the report. A number is what makes a hidden page a visible claim.
Each one is defined here on this site. Open the entry for the full definition and the other words it points at.