The valuation

What the stock is worth, on a stated basis.

The part

What it is

Cost basis matters for the accounts and less for management decisions, where replacement cost and realisable value are usually more relevant.

Write-downs should be visible rather than absorbed, since a stock value that never falls is not a valuation.

The smallest level

The attributes it carries

Each attribute is one of the framework’s shared types. What a date is, and how it is written, is defined once for the whole model — the note here says what it means in this particular place.

Value
What it is carried at.
Money shared type
Basis
Cost, replacement or net realisable value.
Choice shared type
Write-down
What has been written off, which should be visible rather than absorbed.
Money shared type