Explain the GIPS composite construction rules, covering when portfolios may move between composites, when new portfolios must be added and when terminated ones must be removed

Portfolios may not move from one composite to another unless the client changes the mandate or the composite is redefined, with documentation; moving them because of performance is prohibited, and past results stay in the original composite. New portfolios must join according to a documented policy applied consistently, typically at the start of the first full measurement period after the firm has discretion and the assets are invested as intended. Terminated portfolios stay in the composite's history up to the last full measurement period they were managed; removing them would create survivorship bias. Firms may set minimum asset levels or significant cash flow policies that temporarily remove portfolios, but these must be defined in advance and never applied retroactively.