How about a couple of pictures. First, let me re-write your OptoScript a little w/some comments:
A; // do something here, then loop on these other loops, then do it all again if (ending when) A1 is true
B; // do this, do the next loop, then do it if B2 is true, forever, until B2 is true
until C3; // maybe bail out of this inner loop (which we might come back to multiple times depending on outer loops)
until B2; // bail out of this loop when B2 is true
until A1; // bail out of this loop when A1 is true
Here's the equivalent in blocks.
Hope that helps!