Hi,
This is like cardinality in web dynpro abap. We can compare segment as line of internal table.Internal table use dynamic memory allocation so need to specify number of lines.If you specify the segment maximum number say n that means the idoc can has n number of lines(segment typ) at run time.If you include more number of lines in your program while creating idoc it will giva syntax error.
Suppose let sales order Idoc type sal and it has 2 segments header-----hseg
Item segment----iseg
If you set maximum number of segments of hseg is 1and iseg is 10
That means idoc can has header data of one sales order and 10 items data of that sales order.
If you set hseg max is 2 then you can include header data of two sales order in one idoc.
Similarly minimum of segment also. If violate the segment max,min assignment ,we will get styntax error,
So segment max,min use to restrict the amount of data that we can include in one idoc.
Regards,
Sreenivas.