In a recent SAP Professional Journal article, SAP ABAP consultant Faisal Altaf explained how to use implicit enhancements, which allow you to add custom code to SAP's standard code without doing any actual modification. Faisal wrote a companion piece to that article, showing a real-world example of using implicit enhancements.
His example, in "How to Fill a Collective Number with an Automatically Generated Number or Purchase Request Number for an RFQ," Faisal explains how the collective number (Coll. No.) field must be filled manually in requests for quotation (RFQ), but that this becomes a burden of time and allows for too much error. The process can be automated by making the field itself optional (so that the standard SAP code doesn't overwrite what you do) and then using an implicit enhancement to automatically fill the field. In following the process in the article, you bypass the manual step entirely.
The reasons for using this process are varied, but here are a couple of examples Faisal presented:
A collective number is required in transaction ME41 for almost every business. While creating a request for quotation (RFQ), you have to add the collective number manually. You can get multiple quotations against one purchase request (PR) from different vendors. You can use this collective number to collect all quotations against one PR or against one material.
For one example, say a company wants to purchase a laptop. First, it creates a PR for this laptop using transaction ME51N. Then it creates an RFQ for vendors with reference to the created PR using transaction ME41. If the company sends the RFQ to 10 vendors, then it has to create 10 RFQ documents. When it gets a quotation from all vendors, it needs a common ID for the quotations so it can compare them and determine the lowest price. In this case, it can use the collective number (stored in the Coll. No. field) to retrieve and then compare these prices. By default, the user has to enter this collective number manually, which is time consuming and allows for error if the user enters a number incorrectly. As a second example, imagine the company wants to send an RFQ without creating a PR. In this case, it needs to put an automatically generated number into the Coll. No. field.
For the full article, SAP Professional Journal subscribers can go here. For more information about SPJ, go here.