As of right now, you can only rotate bricks, not flip them.
When I say flip, I mean, well
If you rotate
Thrice, you get
But if you flip it you get
Which is useful for large DMs and such where symmetry is important.
I have implemented my own hacky version that basically turns the brick position setter into this:
%newBrick = new fxDtsBrick()
{
position = vectorAdd(%startPos, rotateVector(getWord(%brickStr, 0) * %modx SPC getWord(%brickStr, 1) * %mody SPC
getWord(%brickStr, 2) * %modz, %rotChange));
And then I have %mody/%modz/%modx set to -1 through some client variables and servercmds.
It works, but I'd like to see an official and more polished solution.