is it assential to assign the storage type to the material master
and in movemnt type is it necessary to assign the storage type? it shouldnt be because for differnt material there are going to be different storage type?
how the system comes to know that this storage type is interim for a moement type ?
Based on different material characteristics, you will divide the materials into various storage types, and in the material master you are not assigning the storage types, you are assigning the Indicators for each and every storage types for Stock Placement and Stock Removal.
All the Interim Storage Types are starts with Numeric "9" / "8" etc. Others are predefined like STA, STB.
You need to go through help once on WM, it is very clear in help.sap.com.