Since recently there have been some discussions and two meta posts about the General Reference reason, although it was called differently, I decided to post this scheme taken by the blog post "Are Some Questions Too Simple?" posted by Jeff (I invite you to read it):
Beware of Borror0's diagram (that's the diagram you posted), as it sometimes drives to close questions that are not in fact general reference questions.
Sometimes, there are Google hits for a question, and those hits are superficially ok, and the question is not particularly riveting (say, the meaning of a phrase), and yet the question is not general reference. The problem with this diagram is that it misses one criterion: the answers found in this way should be reliable, and visibly so. Since it is difficult to evaluate the reliability of some random website when you don't know the answer to your question in the first place, googling is the wrong approach.
I recommend a different approach to general reference questions:
If the answer is easily found by looking up the obvious entry in a dictionary, encyclopedia or other reference work, then the question should be closed.
To put it succintly, general reference is “wikipede it”, not “google it”.
On French Language & Usage, we tend to close general reference questions as too localized. The reasoning is that when it's easier to look up the answer in a dictionary than on Stack Exchange, having the question on Stack Exchange “is unlikely to ever help any future visitors”.
CW; feel free to add a German translation.