Level one: ((subst:uw-vandalism1)) This is a gentle caution regarding unconstructive edits; it encourages new editors to use a sandbox for test edits. This is the mildest warning.
Level two: ((subst:uw-vandalism2)) This warning is also fairly mild, though it explicitly uses the word 'vandalism' and links to this Wikipedia policy.
Level three: ((subst:uw-vandalism3)) This warning is sterner. It is the first to warn that further disruptive editing or vandalism may lead to a block.
Level four: ((subst:uw-vandalism4)) This is the sharpest vandalism warning template, and indicates that any further disruptive editing may lead to a block without warning.
Level four-im: ((subst:uw-vandalism4im)) This warning template should be used only in the worst conditions of vandalism. It indicates that this is the only warning the target will receive, and that further disruptive edits will result in a block without warning.