From the Agfa pdf:
The developer concentrate is topped up to the desired final
volume with water at about 30 °C/ 86 °F and stirred well. The
developer is ready for use after cooling to working temperature.
The concentrate should not be stored in its plastic bottle after
part quantities have been removed.
Stock solution (1 + 3): If the complete quantity is not completely
used or different dilutions have to be produced, it is advisable to
mix a concentrated stock solution (= 1 part concentrate + 3 parts
water). This solution can also be used undiluted as a specially
powerful developer (see dilution table).
Normal dilution (1 + 7), (1 part stock solution + 1 part water):
This dilution is recommended if the developer is to be used for a
lengthy period with a low daily throughput. Topping up with the
same solution is only necessary if the tray level falls too low.
The storage life at the normal dilution is about one week.
Economy dilution (1 + 11), (1 part stock solution + 2 parts water):
Economy dilution is particularly efficient if there is a high daily
throughput and the tray contents are exhausted fast. They
deteriorate faster (within one day) but their yield is higher, so that
costs are kept low. To maintain good uniformity developer carryover
should be made up several times daily with the same quantity
of fresh solution.