<i>please tell me is it necessary to use of data element with in data type.if it is necessary why?.or it is not necessary why? </i>
No it is not always necessary to use data elements to define a field of the table. You can choose direct types and define the attributes of the field. You use data elements when you think that there will be several fields that will use the same attributes such as field labels, type, length, search helps, etc. That way, you can just change in one place and all the fields that refer to it will attain the new attributes because they refer to this data element.
<i>what is the use of event start of selection.is it necessary to use if yes why?or if it is not necessary why? </i>
In addition to what others have said, you have to remember one thing is that lack of event specification will make all the code as start-of-selection code. So, if you don't want the code to be executed in the particular order, then you don't need to specify the events. But if you want certain code to be executed after such and such has happened, then you need the events to be specified.
Srinivas
Bluesky
