Management of Structure Gaps in Installed Base Management 
You can mark components with type product and object as structure gaps within an installed base. These structure gaps are used as placeholders and have their own symbol. This makes it possible to remove an individual component without losing the substructures that are linked to this component.
Technically, structure gaps are components of type Product or Object whose corresponding reference to one of these objects is marked as not valid.
Structure gaps can occur as follows:
Initially, by marking the component type when the entry is created.
No reference data is available when you create a structure gap in this way. This means that:
For an object structure gap, no object ID or object family is assigned, nor can they be entered.
For an item structure gap, no product ID is assigned, nor can it be entered.
You can enter reference data using the insert process.
By removing the component. In other words, the component is identified as a structure gap while retaining the existing reference by replacing the symbol. The component-type specific input fields can no longer be edited.
The corresponding reference is no longer valid; the reference data is still displayed, however. It can be replaced later on by a different reference or by the same reference. As a result it is possible, for example, to mark objects as being removed from a hierarchy, but still retain the information that is assigned to the component (such as counters, partners, address, qualifications and warranties) and the structure of the whole hierarchy. Once it has been removed, a component of type object could be assigned to a different installed base hierarchy.
The reference data is displayed in fields that are not available for input. If this data is no longer available, for example because the object is archived, then the corresponding fields are blank. (This is the case for initial structure gaps.) Furthermore, references that are not available do not create any error messages, since the reference data is not validated.
Note
You can also delete components permanently. To do so, cut the component and do not reinsert it in a different position. This sets a time boundary for the validity of a component. In other words, if you view an installed base at the time before a component was removed (in the past), all component information is available at that point in time.
In the installed base, select the component that you want to remove.
Under Object Component-Specific Details or Product Component-Specific Details, choose Dismantle.
The component is identified as a structure gap while retaining the reference.
Save your changes.
In the installed base, select the structure gap where you want to insert a reference to a product or object.
Under Object Component-Specific Details or Product Component-Specific Details, choose Install.
You enter the component-specific information.
Save your changes.