It's [ size ]. I think it ranges from 1-4, but you'll have to experiment.
You can edit your post using the edit buttons in the bottom right of your post. The darker grey one with the lightening bolt will allow you to edit your post in place (without the full editor), while the left-most button will open the full editor. Sometimes you'll get a permissions error with the quick edit (especially if you use the UK site), so you might have to use the full edit.
yep as soon as i tried to edit the message i get permissions error. i couldnt see the button at first because it is white as is the background. so i had to look for it. but your rite it doesnt work properly on the uk forum for editing.
thanx for the size=number pointer... got it working first time...