Positive and Negative days in the Master Planning

Hi forum,

I want to implement master planning for one of my client. so i went through the documents of master planning, but i didnt understood the concept of positive and negative days…so any one can explain me the concept with taking some example…any sort of help is appreciable

thanks in advance



They are kind of similar but the opposite [:D]

With the positive days this is the number of days you are willing to allow positive inventory to handle requirements. Therefore if you haave 100 in stock and an item is required in 70 days do you want the system to suggest a new planned order, or do you believe the inventory will cover this future demand. I always set this to 100 days, or some lengthy period assuming that any long term future orders will be met my the time we reach them from either inventory on hand, or a purchase order triggered for a safety stock or large demand between now and the demand.

With the negative days this determines how long you are willing to wait, with negative inventory, before ordering new replenishments. If you set this to 0 a new planned purchase order will be created. So if you have a purchase order coming in in 30 days and a sales order due for shipment in 28 days time then a new purchase order would be raised. If this was set to anything except 0 it would give you an action message in planning. Again I would recommend a high setting, and let the planning engine suggest action messages, if you set this to 2 days and you had a purchase order due in 10 days and a sales order in 5 days and a 3 day lead time it would raise a new purchase order, whereas I prefer to get the action message and then decide if I can actually move it or load a new one.


I having the same problem that satya had.

We are installing AX, and we have some doubt regarding these positive days.

We are using this in the Periode parameter (coverage code); but does this parameter will be use to consume the mini stock only? I assume that otherwise, an order would be proposed.

Thanks to all for your reply


You have the same problem that you do not understand planning or the negative/positive days?

No the negative and positive days are not used to “consume” minimum stock, this is the trigger point and if this date moves the plan will change.

Thank you AdamRoue for your reply

Indeed it’s the positive and negative days that are nor clear for me:

The negative days (Example 2) means that an customer order could wait 2 days a potentiol production order before to generate a previsional order.

In some other words: Today (30/03/2011) negative days: 2 and a an order planned for 04/04/2011 the system would propose me an order to response to the customer (difference in date > 2) but if I do have already planned and order for 01/04/2011(difference <2) this will allow the delay and accept a backorder for this day.

Regarding the positive day. It’s more confusing

Let’s say I do have 1000pc in stock. I have an order for 1200pc what so ever the positive day, the system should propose me to produce at least 200 pc (regardless minimum stock)

Let’s say I do have 1000pc in stock. I have an order for 200pc, the system should take the part in stock to deliver the customer order.

What is the influence of the positive day so?

I do not understand that the system could propose me to produce part if I have them in stock…

You see something is wrong in the way I see it.

Thank to all


The system will happily suggest you make something you do not need if you configure it in this manner.

Your positive one is incorrect, the 200 will come form the 1000, no influence of the positive days here. It is if you have a purchase order coming in early and you are over filling stock - how many days do you want to allow overstocking essentially.

If you are using coverage periods and you set the negative and positive days to the coverage period you will always get rescehduling messages in any instance and then you can choose to act on them or not. Anything else is set and it depends where the supply and demand balance falls in relation to these days as to what action is undertaken.


If I understand well it’s just a matter of wrning message to postpose orders or to advance order (production orders or purshasing order)

Is that true?

Not really it does depend upon the setting.

If you postive and negative days are the same as your coverage period they can have no impact. Because they have no impact the standard action message would appear on the existing order to tell you what to do.

The difference is if these figures are not the same as the coverage period, then the demand and supply pattern has to take into consideration the impact, and action suggestions and messages based upon how you have configured these days.