I am interested in a certain result which says that if we have an open cover $F_i$ of a sheaf $F$ with each $F_i$ representable, then $F$ is representable. The reason I am interested in this is because I am learning about the construction of the fibered product of two schemes (over a fixed base scheme) using representable functors.
Now the only reference I have been able to find is supposed to be proposition 0.4.5.4 in EGA mentioned by Akhil Mathew here. But how do I find this result in EGA? There are so many volumes/chapters that I get confused! If I understand correctly, the 0 in the beginning followed by 4 means chapter 0 of EGA IV yes? But I can't find it there. Can someone familiar with EGA help me please?