Abiblo Finance - Account Payee Only
It is a sentence being placed between 2 vertical lines mostly in the cheque from the United Kingdom. This will make the cheque non transferable as in Cheque Act 1992.
The purpose is to avoid the cheque being endorsed and paid to account not belonging to the payee.
In some circumstances, the bank may argue that they acted in good faith and without negligence if the cheque being endorsed is honoured by the bank.
New cheques are printed with "account payee only" or A/C payee. The words not negotiable are added.