Sometimes things work out that way. But a new official version of a W3C spec is not just "tacking it on." If data or software claims to be compliant with some v

Sometimes things work out that way. But a new official version of a W3C spec is not just "tacking it on." If data or software claims to be compliant with some version of the relevant W3C spec, they almost always actually are. And while the W3C specs can be a pain in the ass, it's because they're fairly precise and cover most of the edge cases.