Is it ok to include an image from Wikipedia or Wikicommons directly, i.e using the ![<title>](<URL>)
or ![<title>][<num>]
syntax?
Because TeX.SX is also under a wiki license it would seem ok, but I'm not an expert in such things.
The reason I ask was because of Dimensioning of a technical drawing in TikZ which links a technical drawing http://en.wikipedia.org/wiki/File%3aDIN_69893_hsk_63a_drawing.png, which might be better of be included in the question to save people the extra click and make the question easier to understand.