Product Hierarchy

Standard SAP provides Product Hierarchy in 5+5+8 bits which means you can enter three levels of Hierarchy and each 1st and 2nd Level with 5 numeric values and the 3rd level with 8 numeric values but this format is not  the way you want to define hierarchy may be because you have more levels of hierarchy. In Such a case you have to follow as i suggest below.

Note: In my case I am taking 9 levels and each levels with 2 digits. Remember !!! I cannot go beyond 18 Digits total no matter how many levels I have so Mathematically, you can have maximum of 18 levels.

Path: Logistics General-Material Master-Settings for Key Fields-Data Relevant to Sales and Distribution-Define Product Hierarchies-Define Product Hierarchies.

Step-1 

Click on Domain Radio Domain and Create a Domain  On tab page - Definition Enter - Data type - Char, no of character - 2.

Save and Back.

Step-2

click on Radio Button 'Database Tables' Enter PRODH Click on change. and Enter is in the Screen Shot.

Step-3

Enter the Domin that you have created as per example it ZPRODH in DATA TYPE tab Page but to make Changes click on Edit-Modification Operations-Switch off Operations.