don't use comma-separated multiple values

[VladimirAlexiev]

oml:defaultTargetAttribute vann:usageNote "Can also have multiple values (comma-separated)."

Using multiple comma-separated values is a bad semantic practice and you must not promote it.
Instead change to "Can also have multiple values (use the same property several times)."`

In other words:

oml:defaultTargetAttribute "petalWidth, petalLength". # BAD!!!
oml:defaultTargetAttribute "petalWidth", "petalLength". # GOOD