Distribution of Samples among the employees

Hi

My client is in the process of migrating in SAP from legacy ERP system.

Company is a publisher and sells books.

Every month company distributes free sample copy of a specific book among all its employees working from 7 different location.

I need to create a functional specification for this

Biz Overview

would you please guide me for writing this functional specification please?

I suppose I need to create employee as a customer.

I will need to create a book( new material), need to maintain stock in the goods issue storage location

I need to create a distribution list to include all the employees

There needs to  be a program logic that will automatically create a '0' value invoice, for that the program will check the publication date and work backwards and will calculate release to the warehouse. Warehouse picks and dis patches these orders. A0 value invoice needs to be generated

Th

Thanks

Sangeeta