The design has exactly three moving parts, and a grant agreement states all three.
The metric. What the company must achieve. Common choices are financial, such as revenue, earnings per share or return on invested capital, or market-based, such as total shareholder return measured against a named peer group or index. The distinction matters to the holder because a market-based metric depends on the share price, which is the same thing the award is paid in, so a bad stretch hits the count of shares and the value of each share at once.
The performance period. The window over which the metric is measured, commonly several years, and generally longer than the annual cycle a cash bonus runs on. This is what makes the award a retention device as well as an incentive: the result is not known until the period closes.
The payout schedule. A performance award does not simply pay or not pay. Public company disclosure is built around three points, and the Commission defines them: threshold is "the minimum amount payable for a certain level of performance under the plan", target is "the amount payable if the specified performance target(s) are reached", and maximum is "the maximum payout possible under the plan". Below threshold the award pays nothing. Between the stated points the schedule usually interpolates. The spread between threshold and maximum is a plan design choice, not a standard, so the only reliable source for it is the plan document or the employer's own disclosure.
Why the award is reported separately from a time-vesting grant. Under the SEC's rules a registrant must report equity incentive plan awards in their own columns, at threshold, target and maximum, and must report the grant-date value of performance-conditioned awards "based upon the probable outcome" of the conditions. That is a different number from the face value of the same quantity of time-vesting units. Anyone comparing two job offers, or reading a proxy statement, is looking at estimates of an uncertain amount rather than a fixed one.
Certification is a real step. The performance result normally has to be determined and approved by the compensation committee before anything is delivered, so the delivery date can trail the end of the performance period by weeks or months. That gap has practical consequences: the shares are valued for tax on delivery rather than at the close of the period, and an employee who leaves in between may be outside the award entirely depending on what the plan says about termination.
Two things this page deliberately does not re-derive. Once shares are delivered, the tax and withholding work exactly as they do on any unit award, and the schedule mechanics that decide whether an award vests in slices or all at once are the ordinary vesting rules. Both belong to their own entries.