Everything you need to know about Fulfillment Rules for warehouse selection and how to create/edit them.
Fulfillment rules are used to determine the conditions and priorities for selecting a shipping warehouse based on a sales order. Fulfillment will use the sequence to check the available-to-sell (ATS) inventory for each warehouse. This is a way to select which warehouse to ship from. The fulfillment process typically kicks off once a Sales Order (S/O) has been put in the status of "ReadyToShip." This creates a temporary document called a Pick Ticket (P/T) that is sent to the warehouse.
The fulfillment rule follows the available inventory of specific items and the ATS data and will make sure that P/Ts are generated to pull from the right location(s). For example, if you have 10 of an item in one warehouse and 10 in another and you get an order for 20 items - the P/T will reflect that.
To set this rule, starting in ERP, you will go to Admin Tools > Product Settings > Fulfillment Rule Entry. 
Here you will see any existing rules created during onboarding.
By clicking the plus sign next to the rule, you can assign warehouse priority by clicking the dropdown arrow and selecting from the warehouses listed (so if there is inventory in multiple places, it will default to pulling from one warehouse first). You can set a priority order so if there is no inventory in the first priority warehouse it will switch to the second (third, and so on). If you have multiple warehouses, you will always want a Default rule.
For non-default rules, you can assign states to specific warehouses so that - for example - orders with shipping addresses in the certain states (image 1) or Zip Codes (image 2) will only pull from the warehouse you specify here. To add States, click the drop down arrow and select your desired states. To add Zip Codes, just type in your desired code and either press + or hit Enter.
You can further customize by assigning certain channels to each warehouse if you prefer to segment your orders that way. Simply click into the Channel Account field and a dropdown will appear that you can scroll through to select. You can also start typing to narrow your search. As you can see from the image, I began typing "fa" and the search is returning all channels beginning with "fa." To remove a channel, click the x next to the channel name.
For each rule you want to create, click Add Line. When you are done, click Save.
Click Yes.
