[deutdeut]

My book has a problem like this:

Name the compound CH3C(OH)=C(OH)CH3

the answer is trans-2,3-dihydroxybut-2-ene

But isn't the functional group -OH is the principal functional group prior to C=C group and it should be designated as the ending?

Hence can the name be trans-but-2-ene-2,3diol?

[Custos]

What is more annoying is that the structure doesn't make sense from a chemistry perspective. For one thing the name is the enol form (left structure) of the keto alcohol - more likely to be the predominant structure - and the trans/cis isomers will be easily inter-convertible. I understand that this is a "nomenclature problem" but you would at least think a text book would stick with realistic structures. 

[deutdeut]

So is the name correct or not?

[Albert]

trans-but-2-ene-2,3diol?

I believe this to be the best answer (your book's, though, is not totally incorrect).