/usr/share/hunspell/th_TH.aff is in myspell-th 1:3.3.0-4+deb8u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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SET TIS620-2533 REP 4 REP ·Ã « REP « ·Ã REP Ê « REP « Ê