Revaluation model governs carrying amount adjustments for PPE, directing OCI treatment for gains and profit or loss for excess losses. An entity must choose either the Cost Model or the Revaluation Model for subsequent measurement of PPE and apply it consistently. Under the Cost Model assets are carried at cost less accumulated depreciation and impairment. Under the Revaluation Model assets with reliably measurable fair value are carried at revalued amount (fair value at revaluation less subsequent depreciation and impairment), with revaluations at intervals sufficient to avoid material divergence from fair value. Entire asset classes must be revalued; first-time upward revaluations go to OCI as revaluation surplus while first-time downward revaluations are charged to profit or loss, and subsequent increases or decreases are applied against existing surpluses with excess effects through profit or loss. Tax effects follow the income tax standard.