When a teacehr creates a new outcome, the box to make a Standard Outcome is unclickable. However, if you save the outcome, and then edit it, the box can now be clicked.
This has the potential of allowing teachers to create system wide Standard Outcomes, which is not desirable.
Yes - you are right - I tested this and then I found that it is a bug that was reported a while ago and still unresolved. MDL-27619 Perhaps you'd like to comment on that and include your version of Moodle if it is still an issue in later versions.
I've just added a patch to MDL-27619 and submitted it for peer review. I would've done this long ago if I'd known about it sooner - we don't use Outcomes here, so I didn't realise that they suffered from the same issue as scales...
-Paul
