A plan structure identifies the different subfamilies of parts that are grouped under a top-level parent Level 0 master-scheduled part. Plan structure is a generic definition used to facilitate two-level master scheduling.
IFS/Master Scheduling (MS) uses plan structures to disaggregate family forecasts down to individual Level 1 master-scheduled parts. It is also used to aggregate data for Level 1 parts back up to the Level 0 family to which they belong.
Plan structures are divided into three elements: the structure header, the structure alternate, and the structure line items.
A structure header is where the the part, site, and revision are identified. A plan structure can be of Manufacturing structure type.
A plan structure may have several structure header revisions. A structure header is automatically created when a new part revision is created for an inventory part of part type Manufactured or Purchased, and the material requirements planning method attribute is set to O in the Planning Data tab of Inventory Part. If the part is a manufactured part, the structure header is created with the manufacturing structure type. If the part is a purchased part, the structure header is created with the purchasing structure type.
A structure alternate defines the state of the plan structure. Because a plan structure can only have one alternate, indicated with an asterisk (*) in the Alternative No field, only the status of the alternate–not the structure alternate–is displayed for a plan structure.
The state of the structure alternate indicates how the structure information can be used. The ability to change the component records depends upon the structure's state, defined in the Product Structure tab of Product Structure, and the site's Structure Update attribute, defined in Site/Manufacturing. Possible states are:
| State | Description |
| Tentative | A structure alternate is created in Tentative state and, normally, this is the default value. This state indicates that the structure alternate is not yet usable, and the structure data will not be used by Planning or Manufacturing. Components may be changed in this state. |
| Plannable | A structure alternate promoted to Plannable state can be used to calculate cost and planning information, but is still not used for Manufacturing. Components may be changed in this state. |
| Canceled | The structure alternate has been canceled and will not be available for use in Manufacturing or Planning nor used to generate costing information. You can change to this status at any time; however, once in this state, only the status may be changed. |
Structure line items are the components of the plan structure. Each line item identifies either a subfamily (parts with planning method T) or a Level 1 master-scheduled part as well as the quantity per assembly. The Quantity per Assembly column should typically hold a value between 0 and 1. This indicates the percentage that the subfamily or part constitutes of the parent family.
The quantity per assemblies for all subfamilies or Level 1 parts of a parent family should typically total up to be exactly 1. When the total exceeds 1, a warning message is displayed to users, who can still commit the data to the database. This total will exceed 1 when users typically want to overplan a subfamily or part. Another restriction is that a subfamily or Level 1 part can belong to one and only one plan structure (or top-level family).