What is the purpose of 制 in this sentence 夏时制开始 Just received this in a message from a friend trying to determine what time we meet this coming Sunday.


  星期天几点开踢? 夏时制开始


Daylight savings starts early this Sunday at 2am.

So what is the purpose of 制 in the phrase 夏时制开始? 

I see from wiktionary that 制 can have the meaning of "establish" so is 制 included to indicate that daylight savings is starting on that particular day (which is Sunday by context of the previous sentence)?
From speaking to many mainland Chinese, 夏时 means daylight savings. If a Chinese speaker knows about daylight savings, 夏时 is quite clear. 夏时制 is more clear especially for Chinese who aren't familiar with daylight savings. The three words together express "system of daylight saving" loose translation. 

Honestly, would a non-American English speaker be able to know what daylight savings is without previous knowledge of the concept? I don't think so. I can imagine less worldly Chinese not understanding either of the two above phrases unless the concept was carefully explained to them.