The goal of any measurement is to minimize the amount of uncertainty, or error, in the measurement. By minimizing measurement error, accuracy is increased.

Mandrel-wrapping is one such method for reducing measurement uncertainty, while Encircled Flux reduces measurement uncertainty even further.

It is important to note that Encircled Flux is not something that technicians test for in the field. Rather, special reference cables called mode controllers ensure Encircled Flux "compliance". More on mode controllers later.

So, if testing a multimode fiber link requires EF compliance, which is a requirement for the TIA-568-3.D standard, technicians must ensure that EF-compliant test methods are followed.

However, due to variance between different multimode test sources and reference cables, EF compliance cannot be fully ensured by current reference methods, such as mandrel-wrapping.