var country: ByteArray
This field can take three different forms:
\0\0 means any.
Two 7 bit ascii values interpreted as 2 letter region codes
(US, GB etc.). The high bit for both bytes is zero.
An UN M.49 3 digit region code. For simplicity, these are
packed in the same manner as the language codes, though we should
need only 10 bits to represent them, instead of the 15.
The layout is always big-endian irrespective of the runtime architecture.