With my data, I have Delivery Zones. Each Zone has a list of Postal Codes, Items Applicable, and a schedule. As a Sales Order is created, the delivery dates for each item are validated against the delivery zones, ensuring that our fulfillment schedule is followed.
The “Options” for your Table Multiselect field should be a Child Table with a Link field and not the Link directly. Table Multiselect is like a Child Table with just a single field. So for this, you will have to create a child table DocType with a Link field for Item and then use that child table DocType in your “Options”
Steps: https://docs.erpnext.com/docs/user/manual/en/customize-erpnext/articles/table-multiselect-field
Ah! Okay, I read the doc but was still confused! This makes sense.
In the case of my scenario, I needed to make a “Delivery Zone Item Applicable” DocType (with the Link of “Item” only) and have that be the Option under the Table MultiSelect field.