Which of the following is NOT one of the five initial decisions for constructing a trading system?

The choice indicating "Utilize only short-term trades" is not one of the five initial decisions for constructing a trading system because it implies a specific limitation on the type of trades to be considered, rather than addressing the broader framework necessary for system development.

In developing a trading system, decisions typically revolve around the overarching strategy, the time horizon for trades, risk management, and how frequently to update or refine the system. The first decision about the time horizon helps establish whether a trader is looking to engage in short, medium, or long-term trading. Defining a risk control plan is vital, as it ensures that the trader has strategies in place to manage potential losses. Establishing a time routine for updates allows for adjustments to be made based on new data and changing market conditions.

Choosing to exclusively focus on short-term trades can be a part of a trading strategy but is not a necessary or fundamental initial decision for constructing a comprehensive trading system. This choice restricts the trader's options rather than providing a framework for broader decision-making.