nl_tokens: Rule for validating a value exists in an enumerable list .
pl_tokens: function enumerable ( rule , value , <mask> , errors , options ) { rule [ ENUM ] = Array . isArray ( rule [ ENUM ] ) ? rule [ ENUM ] : [ ] ; if ( rule [ ENUM ] . indexOf ( value ) === - 1 ) { errors . push ( util . format ( options . messages [ ENUM ] , rule . fullField , rule [ ENUM ] . join ( ', ' ) ) ) ; } }