As a U.S. person, I have never seen this second notation. My first instinct was that it was 3.14 multiplied by some error factor(s).
In my experience, there tends to be a difference in notation between pure math courses and other scientific or statistical fields. In math we would tend to write $\pi \approx 3.14$. In a statistics or programming text I tend to see $\pi = 3.14$, where the significance is implied by the number of decimal digits, or in narrative text, or in the context of a certain section.
For example, I think it's legitimate to write "Rounded to the hundredths place, $\pi = 3.14$", or, "The values in this table are accurate to the 4th decimal place" or somesuch.