Let's say you've seen some code that you don't fully understand, but could be an exposure, or perhaps a failed mitigation or something. Rather than committing yourself to an @exposes or @mitigates, it could be flagged using @review (or whatever). This would then be included in threat model reports, and could help guide investigations into areas of uncertainty for further review.
I'm thinking something like
@review COMMENT [for BOUNDARY:COMPONENT] [(REFS)]
e.g.
@review calling a validation but not sure this meets the requirements for Web:LoginForm (#123)