QUOTE(musbird @ Aug 23 2009, 08:56 PM)

I understand that where music goes more than 5 lines above the stave, the composer will abbreviate with "8ve".

Sometimes. It partly depends on the instrument (for example flute and piccolo players are used to reading many ledger lines).
QUOTE(musbird @ Aug 23 2009, 08:56 PM)

So in the G5 exam, if you are asked to transpose a piece of music by an octave - Am I right to presume that you would simply pop a square bracket over the notes and write 8ve.
No! They want you to do it properly, even if it does involve drawing lots of ledger lines. Also, not all the examples where you have to transpose up an octave will involve such high notes.
QUOTE(musbird @ Aug 23 2009, 08:56 PM)

Although it's probably a really silly Q, ive never done a theory exam and am going in at grade 5 so I need to be 110% sure...
I've just brought a book called "take 5 and pass 1st time"..halfway through it and its brilliant - explains everything so easily.
It's not a silly question; I can see your logic. Are you having lessons or teaching yourself?
QUOTE(sarah123 @ Aug 23 2009, 09:00 PM)

you don't always get 8ve above notes that are more than an octave above the stave. It's only really if substantial sections are almost entirely up in the stratosphere that they're used. You probably shouldn't use them in a transposition question.
It can be used even for single notes, I think. Pretty sure I've seen this.