I ran across the implementation of XML_name. It is a functor used to validate each single character in an XML name. The initialization of a stack-based look-up table everytime the functor is called puzzles me (see excerpt below). void operator()(CharType t) const{ unsigned char lookup_table[] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0, // -. 1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0, // 0-9 0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // A- 1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,1, // -Z _ 0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // a- 1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0, // -z 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }; if((unsigned)t > 127) return; if(0 == lookup_table[(unsigned)t]) boost::throw_exception( xml_archive_exception( xml_archive_exception::xml_archive_tag_name_error ) ); } Is there any reason why it was done this way? For threading issues? Thanks, Sean