Criteria 4 and 5 of the Basel definition of Additional Tier 1 capital seem to contradict each other regarding the required maturity of these capital instruments.

Criterion 4 says: [The instruments is] perpetual, ie there is no maturity date and there are no step-ups or other incentives to redeem.

Criterion 5 says: [The instruments may] be callable at the initiative of the issuer only after a minimum of five years: a. To exercise a call option a bank must receive prior supervisory approval; and b. A bank must not do anything which creates an expectation that the call will be exercised; and c. Banks must not exercise a call unless: i. They replace the called instrument with capital of the same or better quality and the replacement of this capital is done at conditions which are sustainable for the income capacity of the bank; or ii. The bank demonstrates that its capital position is well above the minimum capital requirements after the call option is exercised.

Explain this apparent contradiction and why in practice this may (or may not) be a problem.