The -checked option would specify whether integer arithmetic statements that are not in the scope of a checked: or unchecked: block throws a run-time exception in case of an overflow.
The default is
checked, this means it is not checked.*
If you specify -checked+ (or -checked alone) it is checked.
This has the same behavior as csc's /checked option.
*:default has to be confirmed.
If we agree on changing this, it may be better to postpone the change of default to 0.8 since this will be the official "Screw compatibility!" release (net-2.0, new range behavior, versioning, and al).