Working with Requirements in Sales and Distribution Processing 
Performing transfer of requirements is dependent on a number of factors. They determine whether and how requirements should be transferred and if they should be checked against planned requirements. The transfer of requirements in sales can be switched on or off by transaction as required. For example, you can switch off the transfer of requirements for inquiries and quotations, whereas you can switch it on for sales orders and deliveries.
For further information on working with requirements, see
Types of Transfer of Requirements in Sales and Distribution Documents Controlling Transfer of Requirements in Sales and Distribution Documents Effects of the Transfer of Requirements in Sales and Distribution Documents Allocating and Reducing Independent Requirements in Sales and Distribution DocumentsYou will also find information on production planning and, in particular, on independent requirements in the R/3 PP documentation as well as information on the availability check in
Availability Check in Sales and Distribution Processing..