Working with Cost Centers and Distribution Rules 
A cost center is a company unit or division that performs a specific business function.
For expenses and revenues that can be assigned directly to a cost center, you define a direct distribution rule. When you create a cost center, SAP Business One automatically creates a distribution rule. You cannot change this distribution rule. The default values of the distribution rule are as follows:
Values in the Code and Description fields are the same as they appear in the Cost Center and Name fields, respectively, of the corresponding cost center.
The dimension and effective period are the same as those of the corresponding cost center.
The Active and Direct Allocation checkboxes are automatically selected.
The value of the corresponding cost center is 100, for a total value of 100.