Meaning of notation in violin part

Question

I've been working on transcribing a score for my own edification, and I've come across a piece of notation in one of the violin parts that I'm not familiar with:

In the third measure shown, the A has two stems (one ascending, one descending), a circle drawn above it, and a numeral 4 written below it. I know that a double stem like this can mean a divisi part; and an open circle can either mean a harmonic or an open string. But I can't figure out what the 4 is supposed to represent. (I'm a brass player, myself, so I'm not familiar with a lot of string-specific notation.)

What, precisely, are the second violins meant to do when they play this note?

Answer 1

The 4 indicates that the A is to be played using the fourth finger on the D string, while the 0 indicates that the A is to be played as an open string. Given the double stop in the fourth measure, I suspect this is to be played as a double stop as well, rather than as a divisi. So each second violinist will be playing the A on two strings simultaneously.