Bryce doesn't use the standard coordinate system in default (Director) view, probably because the different views available would make it very difficult to keep your Axis ass up ;)
However in camera view it falls in line with most other apps.
I almost always use camera view so this isn't a big deal to me.
X= Positive Left/– Right (or 'side to side' depending upon center axis)
Y= Plus is Up/– is Down
Z= the ole Positive in/–out (Pos is towards you/– away)