Hi,
There are 3 stock types in SAP, unrestricted stock, QI stock and blocked stock. You may select any of these three options in MIGO. Refer the help doc: General Information on Stock Types - Inventory Management and Physical Inventory (MM-IM) - SAP Library
The special stocks are different from stock types. As the name indicates, its not ordinary stock and are treated differently in IM. The special stocks cant be selected from the stock types in MIGO. These are dependent on item cat or acc assignment cat in PO or movement types. In special stocks also, you can have the above mentioned 3 stock types. Refer the help doc: Inventory Management: Special Stocks (SAP Library - SAP Retail)
Hope its clear.
Regards,
AKPT