Add comment to constructor of SDDSColumn.

src/Structure/SDDSColumn.cpp

@@ -25,6 +25,7 @@ SDDSColumn::SDDSColumn(const std::string& name,
                                                         std::ios_base::left,
                                                         std::ios_base::right});
 
+    // This code ensures that for each group of flags only one flag is given
     for (std::ios_base::fmtflags flag: numericalBase) {
         if (writeFlags_m & flag) {
             writeFlags_m = (flag | (writeFlags_m & ~std::ios_base::basefield));