在storage type配置里有个选项允许负库存的，如下图：
Indicator: negative stock quantity allowed
If you set this indicator, the system allows you to post negative quants to the corresponding storage type
Use
If you execute movements in the Warehouse Management System (WMS), which require interim storage areas, the total stock in Inventory Management (MM-IM) and in WMS must remain the same. This is possible by posting negative stock to the interim storage area.
Example
You use this field mainly for interim storage areas.
Procedure
You can set whether the system issues an error message (E), a warning (W), or no message (blank) when you post negative stock. You can do this in the Customizing for Warehouse Management under Interfaces -> Inventory Management -> Allow Negative Stocks in Interim Storage Types -> Control of System Messages in Warehouse Management.
1. You define the message type using the parameter MSV in the user master record:
2. In the SAP Menu, choose System -> User profile -> Own data.
3. Choose the tab page Parameters
4. Enter MSV in the field Parameters and enter the value with which you wish to group a certain user (for example 01) in the field Value.
5. In the IMG for Warehouse Management, choose Interfaces -> Inventory Management -> Allow Negative Stocks in Interim Storage Types -> Control of System Messages in Warehouse Management.
6. Create a new entry with the version number you selected (Value) and enter the desired system reaction in the field Message type (E, W, or blank).
Example:
Version
=
Parameter MSV from the user master record
Application area
=
L9
Message
=
040
Type
=
E, W, or blank
If you have not defined the parameter MSV in the user master record, the system uses version 00.
在D项目的上线后支持阶段笔者发现：仅仅是修改storage type 100里的配置，不勾选’Allow negative stock’是不够的，如果不设置系统消息的属性为E（Error）,则系统还是允许在100里有负库存的，如下图示：
2018-06-16 写于无锡市新吴区
