I think the implication is that a transformation won't be reversible if you don't know exactly what was applied? Like, I've had the situation of seeing a poorl

I think the implication is that a transformation won't be reversible if you don't know exactly what was applied? Like, I've had the situation of seeing a poorly-marked name string and going "I think that's 'Last, First' formatting, but I'm really not certain..." Or if you do any formatting change you'll get bizarre problems like apostrophes becoming directional quotes. But yes, the rule-as-written isn't right, and I'm not sure what was meant.