Android : What is the the double quotation marks in strings.xml used for?

Just a little while ago, I was looking around on GitHub， and I found there were some double quotation marks beside the string value in some strings.xml just like this:

<string name="ClipMmi" msgid="6952821216480289285">"来电显示"</string>

In short I mean this

"来电显示"

For full example please click here.

I don't know what is the "" used for?Because if I remove the "" beside the string value(e.g. "来电显示" change to 来电显示), the output won't change anymore, both "来电显示" and 来电显示 will print 来电显示 as the output.

So does the quotations make any sense here?