filter_add_strn
f = filter_add_strn( f, flimit, "\\2a", 3 );
f = filter_add_strn( f, flimit, x, 3 );
f = filter_add_strn( f, flimit, "\\5c", 3 );
f = filter_add_strn( f, flimit, v, slen );
f = filter_add_strn( f, flimit, prefix, strlen( prefix ));
f = filter_add_strn( f, flimit, " ", 1 );
f = filter_add_strn( f, flimit, attr, strlen( attr ));
f = filter_add_strn( f, flimit, suffix, strlen( suffix ));