Evolution is observable change(s) in all living systems limited to the observed time frame.
Should be changed to "over time". Good scientific procedure requires that a process be reproducible and observable. However, in this case, the concept of "Evolution" generally extends well beyond the boundaries of good science.
Mechanisms should not be classified within evolution.
The reason being that science is incomplete,
(or wrong, as we say in the normal world)
and that including mechanisms is a recipe for disaster for the definition. Take Darwin for example. Good thing he didn't insist that orchard workers kids would have longer arms as part of his definition.
It should be acknowledged that theoretical science is separate from theological musings, and should not be coupled within a standard of a definition.
This should read that
"It should be acknowledged that theoretical science can be heavily biased by theological musings,
and therefore should not be coupled within a standard of a definition."
I burst out laughing when I read at "Talkorigins" that most of the confusion over definition is because scientists are illiterate. (In so many words.) I happen to know that scientists are MOST often, very good and practiced at explaining things in lay language, so clearly the problem is not that.