1option:
2  [no]alt-tokens
3  [no]debug
4  {di|tri|no}graphs
5  [no]east-const
6  [no]explain-by-default
7  [no]explicit-ecsu[={e|c|s|u}+]
8  [no]explicit-int[=<types>]
9  lang=<lang>
10  <lang>
11  [no]prompt
12  [no]semicolon
13lang:
14  K[&|N]R[C] | C[K[&|N]R|78|89|95|99|11|17|2X] | C++[98|03|11|14|17|20|23]
15where: [] = 0 or 1; * = 0 or more; + = 1 or more; {} = one of; | = alternate
16