const char * get_ext_sys_var ( const char * tag ) {
 struct ctl_var * v ;
 size_t c ;
 const char * val ;
 val = NULL ;
 c = strlen ( tag ) ;
 for ( v = ext_sys_var ;
 ! ( EOV & v -> flags ) ;
 v ++ ) {
 if ( NULL != v -> text && ! memcmp ( tag , v -> text , c ) ) {
 if ( '=' == v -> text [ c ] ) {
 val = v -> text + c + 1 ;
 break ;
 }
 else if ( '\0' == v -> text [ c ] ) {
 val = "" ;
 break ;
 }
 }
 }
 return val ;
 }
const char * get_ext_sys_var ( const char * tag ) {
 struct ctl_var * v ;
 size_t c ;
 const char * val ;
 val = NULL ;
 c = strlen ( tag ) ;
 for ( v = ext_sys_var ;
 ! ( EOV & v -> flags ) ;
 v ++ ) {
 if ( NULL != v -> text && ! memcmp ( tag , v -> text , c ) ) {
 if ( '=' == v -> text [ c ] ) {
 val = v -> text + c + 1 ;
 break ;
 }
 else if ( '\0' == v -> text [ c ] ) {
 val = "" ;
 break ;
 }
 }
 }
 return val ;
 }