ss_get_bytes (&s, ss_span (s, ss_cstr (CC_LETTERS)), &type_ss);
ss_get_bytes (&s, ss_span (s, ss_cstr (CC_DIGITS)), &width_ss);
if (ss_match_byte (&s, '.'))
ss_get_bytes (&s, ss_span (s, ss_cstr (CC_LETTERS)), &type_ss);
ss_get_bytes (&s, ss_span (s, ss_cstr (CC_DIGITS)), &width_ss);
if (ss_match_byte (&s, '.'))