I think we should gather a list of all languages that are, by default, allowed to to do things differently on challenges that do not explicitly disallow it. Every question I write it seems that someone asks if, "Can I do X instead of Y?", or if, "Can I have X different from the specified output, my language doesn't support Y?" This is mostly on ascii-art, kolmogorov-complexity and math challenges. I was thinking that maybe we should have a table that people can refer back to in defense of their answers in terms of precision, and other arbitrary language limitations. There's obviously many ways to handle this though, post your thoughts as answers.
Post suggestions for how to solve this problem below.
Examples of Questions on Formatting (See OP Comment Section)
Trailing spaces / newlines examples: 5 Favorite Letters , Kuznetsov's Sequence
Precision examples: Bailey–Borwein–Plouffe Iterations , Compute the Median
Input formatting examples: The Art of Word Shaping , Sort a string, sort of
Indexing (0 vs 1, Mathematica spurred this): Linear Regression on a String
I've seen a lot more but don't have the time to go through each challenge to see which ones people ask about 1-indexing for mathematica, trailing newlines on jelly, arrays of characters in python, non-floating point arithmetic in languages only supporting integers... Etc... It would help to have a catalog of language limitations on languages that have them. It is a small list, to be honest and would be good reference material.