EDI Extending IDOC

Hi frenz,

I've got a requirement that for a particular EDI transmission we dont have some four fields in our IDoc type. Now i just want to know which method given below is better to use;

1) Creating new segments and putting fields into it.

2) Using similar, unsed fields to contain those values.

Which among these two are better?

I expect quick replies b'cos i need it urgently.

Thanks in advance,

Praveen.