This is a conversion PDF from older versions of THOGS into v4 beta, it requires an older THOGS rulebook to be playable. The designer Ilmari Virtanen released THOGS v4 beta as free download in 2012 after development period 2002-2012 due to not enough time to finish a new book and not wanting to keep fans waiting for revision of the rules.
THOGS v4 beta contains:
revised weapon and armor lists
rules for high and low quality weapons
rules for encumberance
new magic potions
revised profession and skill tables, rules and special skills