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The SAP System is equipped with a special lock mechanism that synchronizes access to data onthe database. The purpose of the lock mechanism is to prevent two transactions from changingthe same data on the database simultaneously.

This documentation describes how to use RFC (Remote Function Call) from outside an SAP System, that is, how to write your own RFC functions or to call a function module in an R/2 or R/3 System.The following topics contain basic information:RFC with External Systems [Page 10]Technical Requirements [Page 12]Contents of the RFC SDK [Page 14]Compiling and Linking RFC Programs [Page 17]

SAP Tree and SAP Tree Model are techniques based on SAP's Control Framework that you canuse to display hierarchically-arranged data in tree format. SAP Tree, introduced in Release 4.6A,can be used to display data at the frontend. The SAP Tree Model, new in Release 4.6C, alsoallows you to administer the data within the control instance.The graphic illustrates the difference: The SAP Tree receives application data from the programand passes it to its corresponding frontend component, either directly, or at the nextsynchronization. However, it cannot hold any data itself, which means that to find out attributes ofa node or item other than its key or name, you must program the request yourself on the basis ofthe node key. The SAP Tree Model, on the other hand, incorporates a data management partand also encapsulates a normal tree control instance. All of the data that is passed to the tree isheld within the Tree Model instance as well as being sent to the frontend. Consequently, actionslike searching within the tree take place within the ABAP program, and do not require timeconsumingnetwork communication.

The SAP toolbar allows you to define a separate toolbar in addition to the normal applicationtoolbar:

You can use the SAP Textedit control to implement an editor for entering and working with text. Itcan be used as a simple multi-line editor and as an editor for ABAP code. It provides temporaryadditions that allow you to change the display (for example, to highlight text). Temporary in thissense means that the additions are set and managed at the frontend, but not passed back to thecontroller. The textedit control does not allow you to set permanent format information or usegraphics.