Prior to the existence of HUM, in WM you had storage units (SUs) and in SD shipping units (also SUs). HUM is more or less an extension of the functionality of these through the other modules in the supply chain. I believe when SAP did this they needed to retain the existing SU numbers and functions but wished to have the HU as a universal description. Therefore the old SUs were re-badged as internal HUs whereas the new HUs, which have the ability to move through the modules are described as external. In other words internal HUs only exist in WM.
The HU information is stored in table VEKP (header) and VEPO (item). In the header table you can find Internal HU No (VENUM). This is the internal SAP number automatically assigned as the table key each time you create an HU. However, the HU aslo has an external number (EXIDV) which is the number of the HU that is used when marking the HU. This number allows for a longer ID than the internal number if you want to use.
Here is the documentation for EXIDV.
Short Text
External Handling Unit Identification
Definition
Specifies an external identifier for the handling unit.
Use
The system automatically generates an internal number that must be unique for each system client. The system also needs external identification so that it can uniquely identify handling units.
1. Creating a handling unit:
Identifiers for handling units are determined during creation according to settings in Customizing for number assignment of the packaging material type for the packaging material that is being used. You can also assign default values for identifiers when you create handling units, although these values must correspond to the settings in Customizing.
2. Processing a handling unit
To edit existing handling units, enter the handling unit's identification in this field.
2016-09-02 整理于武汉市经开区
