The reform broke the old system that had been in use for years.
Tips
history
Historically 旧制 often refers specifically to pre-1959 Chinese measures, when 1 斤 = 16 两. The PRC's 1959 metric reform (市制改革) redefined 斤 to 10 两 = 500 g, which is still called 市制 (shìzhì) - the system in everyday use today.
