Field help (BPCGRU1SIH) 

This information can be modified. It is used notably to establish the statistics. It is also involved in the grouping of invoices during the automatic generation of invoices.
It is initialized:

From this field, it is possible to directly enter the group customer whose existence is controlled in the customer table or to use the contextual button to:

It is possible to search a customer or several customer grouped under the same criteria by selecting "Quick customer search". A list of matching items is generated on tabulating to the next field.
For a more advanced search, all fields present in the block can be entered. The list of matches is narrowed down with each tabulation.