that's an extremely selective quotation from the nutshell text the essay which i originally wrote so i'm pretty familiar with it gives three basic check points to verify whether it's likely that an xkcd reference is helpful this reference meets none of them it is at best a trivial and non free illustration of an sql injection attack which has its own article anyway people are prone to arguing that a given xkcd strip provides some unique insight into a subject when this is usually extremely subjective were this actually the case for a given reference then one would imagine that some third party would pick up on this in a reliable source that hasn't happened here so it seems like nothing more than one wikipedia editor's personal judgement wp el specifically notes when external links are appropriate and again this link doesn't meet those guidelines as applied to the rest of the encyclopedia chris cunningham not at work talk