[this restriction is needed because of BIG5, BIG5-HKSCS, GBK, GB18030,
Shift_JIS, JOHAB], and
3. does not consist entirely of decimal digits, or has at least length 4
[this restriction is needed because of BIG5, BIG5-HKSCS, GBK, GB18030,
Shift_JIS, JOHAB], and
3. does not consist entirely of decimal digits, or has at least length 4