Description: An indication of the relative position of this 'child' component among all its 'sibling' components. Sibling components are defined as invPhysEntries which share the same instance values of each of the invPhysContainedIn and invPhysClass objects.

An NMS can use this object to identify the relative ordering for all sibling components of a particular parent (identified by the invPhysContainedIn instance in each sibling entry).

This value should match any external labeling of the physical component if possible. For example, for a container (e.g., card slot) labeled as 'slot #3', invPhysParentRelPos should have the value '3'. Note that the invPhysEntry for the module plugged in slot 3 should have an invPhysParentRelPos value of '1'.

If the physical position of this component does not match any external numbering or clearly visible ordering, then user documentation or other external reference material should be used to determine the parent-relative position. If this is not possible, then the the agent should assign a consistent (but possibly arbitrary) ordering to a given set of 'sibling' components, perhaps based on internal representation of the components.

If the agent cannot determine the parent-relative position for some reason, or if the associated value of invPhysContainedIn is '0', then the value '-1' is returned. Otherwise a non-negative integer is returned, indicating the parent-relative position of this physical entity.

Parent-relative ordering normally starts from '1' and continues to 'N', where 'N' represents the highest positioned child entity. However, if the physical entities (e.g., slots) are labeled from a starting position of zero, then the first sibling should be associated with a invPhysParentRelPos value of '0'. Note that this ordering may be sparse or dense, depending on agent implementation.

The actual values returned are not globally meaningful, as each 'parent' component may use different numbering algorithms. The ordering is only meaningful among siblings of the same parent component.

The agent should retain parent-relative position values across reboots, either through algorithmic assignment or use of non-volatile storage.