This message must not be used to report the movement of securities out of or into a safekeeping account. It reports only on movements that affect the status/availability of the security, ie, movements from one sub-balance to another or intra-position transfers, within that safekeeping account.
This message should also be used when the account servicer confirms an intra-position instruction, ie, following an MT 524.
In case of blocking of shares, depending on your internal processing method, you can use either an MT 566 Corporate Action Confirmation or an MT 508 Intra-Position Advice. The MT 566 is to be used when the securities safekeeping account is debited and another securities safekeeping account is credited. The MT 508 is to be used when the securities remain in the same securities safekeeping account but are given a blocked status.