Flash syntax

hi,

I need help to understand the basic syntax.
like:
iXpos = (mouseX <= lo) ? xhi : xlo;
and
(this.trend == 0 ) ? (checkBoundary() ? 0.25 : -0.25) : (this.trend);

what “?” and “:” stands for

its kind of tricky to search for specific character syntax?:sigh:

thx,
Daniel