The core concept of TradeTrax is the "Asset" (aka "stock item"). An asset is in very abstract terms any item (or stack of items) that can be owned (physically or virtually) and is tradeable. It has the following properties:

The Id is a numerical value that identifies an asset uniquely within the system. It is automatically assigned upon creation and cannot be changed afterwards.
The name (mandatory) identifies the primary kind of an asset. It is possible, even likely, that two different assets share the same name. For example, when TradeTrax is used to track forex trades, it might happen that $100 get bought on Monday for 75€ and another $200 get bought for 140€ on Tuesday. These are two different assets, but both would use the same name: Dollar.
Variants are (optional) subtypes. They are useful when tracking collectibles where the base item is produced in different versions. For example, Coin collectors might use them to track the date of coinage.
Storage location
The storage location is meant to be used for recording where the asset is kept physically. Like a comment, this value has no internal meaning to TradeTrax, but using a structured string is recommended.
Assets may come as stacks of individual items of the same kind (for example, whine bottles in a crate). In most cases, the unit count should be one or higher, but zero or less is allowed as well in order to model borrowed items (e.g. lending out stock shares to a stock broker).
The date when the asset in question was acquired. It is quite possible to "own" an asset without an acquisition date or have an acquisition date in the future (for example, when trading futures on the stock market).
The date when the asset was cashed in on. It is possible to liquidate something before acquiring it (for example, when selling stock on a margin).
How much money acquisition of the asset did cost (per unit). It is possible to acquire something for no cost at all (gifts) or even a negative cost (for example, a scrapyard owner might charge a fee). The cost has a close relation to the acquisition date. When no acquisition date is set, the cost is considered to be "expected".
The amount of money earned (per unit) when liquidating the asset. It is possible to make no money at all or even loose money in the process (e.g. when a perishable goods has to be thrown away and there is a waste disposal fee). The returns have a close relation to the liquidation date. When no liquidation date is set, the returns are considered to be "expected".
For annotations of any kind. Display value only with no internal meaning to TradeTrax.