What is the significance of I in TLIV format of GTPv2 message format?

Question

Each layer has TLV while GTPv2 has TLIV, can anyone explain why?

Answer 1

The Instance field in GTPv2 messages allows the Information Element to get re-used for some other purpose.
A classical example would be of FTEID IE.

In Create Session Request message, within Bearer Context, there could be many instances of FTEID used for different purpose, check the attached image!

Benefit? We need not define different IE having same type information used for different purposes.