The shop order auto reservation logic follows the priorities defined on the Site page:

In addition, reservation can be limited to certain locations based on below hierarchy:

@Björn Hultgren : Thank you so much for your detailed information.

Have a follow-up question:

Earliest Receipt Date : would this apply to the date good have been received to the inventory ? (applicable only for Purchase goods and not for manufacturing)

@Edie Below is the detailed explanation from the documentation:

Define Automatic Reservation

Explanation

This activity is used to define the rules for the automatic reservation functionality. In this page it is possible decide if automatic reservation should be pure FIFO, handling unit optimized or perhaps consider putaway zone ranking. It is also possible to define if receipt dates for FIFO consideration should consider date and time or only date. Furthermore you can decide if created transport tasks with destination move to inventory, should be considered as available to reserve from.

Automatic Reservation Priorities – presets
The application includes five flexible prioritization possibilities in the automatic reservation process. It will be used to sort out in which order to search for and find available items to reserve. These five settings could be combined or leaved out but at least one prioritization value is needed to be set. Below a list of example presets which can be used to understand the impact of the setup possibilities:

Default when creating site:
Priority 1: Highest Putaway Zone Ranking
Priority 2: Earliest Expiration Date
Priority 3: Earliest Receipt Date
Priority 4: Largest Quantity on Handling Unit
Priority 5: Outermost Handling Unit
Handling Unit Optimization: Enabled
Receipt Date with Timestamp: Disabled
Reserve from Transport Task: Disabled

Prioritization is using zone ranking, expiration date and receipt date and HU optimization, i.e. trying to pick the most suitable HU found. If expiration date is null on part records, it will be handled as unlimited expiration date. Handling Unit Optimization checked means that the reservation looks at the available stock from a HU perspective meanwhile having it unchecked means the stock is looked at on a part level, even if the part belongs to a HU

Note that using handling unit optimized set with this combination means that the automatic reservation will always prefer to reserve complete handling units regardless of other setting in priority. So if highest putaway zone ranking is set as highest priority there could still be reservations made from outside the zone if a complete handling unit is found there but not in the highest ranked zone.

Pure FIFO
Priority 1: Earliest Receipt Date
Priority 2:
Priority 3 :
Priority 4:
Priority 5:
Handling Unit Optimization: Disabled
Receipt Date with Timestamp: Enabled
Reserve from Transport Task: N/A

This will prioritize items in order of the actual receipt to inventory, i.e. reserve the earliest received item first, using the timestamp of the receipt. This known as the FIFO principal and by combined it with timestamp parameter set to true means that it will be reserved in the order it was received on the level of seconds. The HU perspective is not taken in consideration meaning that stock is seen as parts only. Note that Handling Unit Optimization must be unchecked to get pure FIFO. If you reserve from created transport task this material will be evaluated from a FIFO perspective otherwise not.

Handling Unit Optimized
Priority 1 : Largest Quantity on Handling Unit
Priority 2 : Outermost Handling Unit
Priority 3:
Priority 4:
Priority 5:
Handling Unit Optimization: Enabled
Receipt Date with Timestamp: Disabled
Reserve from Transport Task: N/A

This definition indicates the most optimized setup for usage of HU. It will trying to pick the HU with the largest quantity, i.e. trying to reserve less HUs as possible (example: if the demand is 20 pcs, a HU including 20 pcs will be reserved in front of two HUs including 10 pcs each). It will also try to pick outermost HU in front of HU being a part of a structure (example: if the reserve demand is 10 pcs and there exists an HU with this quantity, this will be reserved in front of the same type of HU which currently is put on a pallet, i.e. the pallet is in this case the outermost HU). If you reserve from created transport task this material will be evaluated from a handling unit perspective otherwise not.

Note that using handling unit optimized means that the automatic reservation will always prefer to reserve complete handling units regardless of other setting in priority. So if highest putaway zone ranking is set as highest priority there could still be reservations made from outside the zone if a complete handling unit is found there but not in the highest ranked zone.

Expired first
Priority 1 : Earliest Expiration Date
Priority 2:
Priority 3:
Priority 4:
Priority 5:
Handling Unit Optimization: Disabled
Receipt Date with Timestamp: Disabled
Reserve from Transport Task: N/A

The setup should guarantee that items with the earliest expiration date will be reserved, no matters if it stored as pcs or part of HUs. If expiration date is null on part records, it will be handled as unlimited expiration date. The HU perspective is not taken in consideration meaning that stock is seen as parts only. If you reserve from created transport task this material will be evaluated from a expiration perspective otherwise not.

Note 1: When having Handling Unit Optimization unchecked, the prioritization values “Large Quantity on Handling Unit” and “Outermost Handling Unit” is not applicable.
Note 2: The Receipt Date with Timestamp is only applicable if prioritization value “Earliest Receipt Date” is used.

Furthermore, if you use putaway zone ranking and handling unit optimization you have the option to configure an alternative putaway zone ranking to be used at reservation of complete handling units by one demand line. For instance this implies that you can prioritize to reserve complete handling units in bulk zones prior to reserving complete handling units in the picking zone. This is enabled for certain handling unit types and the alternative ranking is entered in the putaway zone ranking.

Upon these prioritizations, there is a base sorting which is the fallback when all flexible prioritizations rules turn out to be equal in the specific case. These are a bit different depending if running with or without Handling Unit Optimization:

Handling Unit Optimized enabled:
1) Total Available Quantity of the requested part in Handling Unit
2) Least of Total Qty Required and Total Quantity available to reserve on the Location
3) Warehouse Route Order
4) Bay Route Order
5) Row Route Order
6) Tier Route Order
7) Bin Route Order
8) The handling Unit ID of the HU from we will do a partial reservation
9) The Lot/Batch No of the stock records
10) The Serial No of the stock records

Handling Unit Optimized disabled:
1) The Lot/Batch No of the stock records
2) The Serial No of the stock records
3) Least of Total Qty Required and Total Quantity Available to reserve on the Location.
4) Warehouse Route Order
5) Bay Route Order
6) Row Route Order
7) Tier Route Order
8) Bin Route Order

Prerequisites

The inventory parts and locations must meet the following prerequisites:

• The inventory location must be a picking location. The inventory location cannot be a floor stock, a manufacturing cell, an inspection location, a shipment inventory.
• The part must not be expired, i.e., the part must be current.
• The inventory part might be connected to a part availability control ID (in the Inventory Part In Stock page). If so, the availability control shall allow reservations.
• The inventory balance of the part at the inventory location must be higher than zero (0) after accounting for all current reservations. Note that created transport tasks can be considered as available to reserve depending on configuration on the site.

@Björn Hultgren Perfecto!! Thank you so much.

Hi @Björn Hultgren  :)

We have just started using the Putaway functionality in APP9, and discovered the effect the ranking have on our picklist reservation. We would like to keep pure FIFO/Priority 1: Earliest Receipt Date, but Site doesn't have the same settings as in your example. Is there another way of getting the same result in APP9?

br Emma 

@EmmaE Unfortunately I believe the possibility to configure the priority order of automatic reservations where introduced in Apps 10 together with the Handling unit concept.

Hi @Björn Hultgren,

This information is great. I have a quick question related to a challenge we are experiencing. The documentation you linked shows that a prerequisite for the automatic reservation prioritization is that the location must be a picking location. Does that mean that the list below is applied before any prioritization done at the site level? Will the automatic reservation always pull from a floor location before a picking location even if the picking location has a higher putaway zone rating and that is priority 1 in our site setup?

Thanks,

Dylan

@dritter The 5 level hierarchy is the primary control of the backflush. And you can configure the system to stop the reservation or backflush on a specific level (for instance, so that backflush stops at the work center inbound locations, but reservations are allowed from picking locations).

Within each hierarchy level, the prioritization is done based on the automatic reservation rules defined on the site.

@Björn Hultgren  Thank you for the help!

I read all the information above I am still not sure how you would configure the reservation process to use LIFO. I know FIFO is implied through the use of the Priority Earliest Date setting, but about LIFO. There is no Latest or Newest Date setting. Sorry we are new to IFS and in our prior system, we actually had a simple setting using FIFO/LIFO/SystemDate/Lot Number, etc, to pick, reserve, consume and ship parts.

​@eknock007 

Unless your business scenario really has some physical inventory LIFO situation for auto reservation, the use of LIFO is mostly in the interest of costs, and IFS captures this in Inventory Valuation Method per Inventory Part or in Site level. 

Further reading on this for you - FIFO and LIFO | IFS Community