The use of the APERAK, of course, must be agreed between EDI partners.
Anyway an EDI partner can ask for an acknowledgement, relating the receipt of the message sent, by means of data element 4343 on the BGM segment level.
Here below the sample of a BGM segment in a COREOR message requiring for an APERAK:
BGM+12:::TRANSPORT CARGO RELEASE ORDER+1234+9+AB'
The qualifier AB stands for Message Acknowledgement and indicates that an acknowledgement relating to receipt of message is required.