The URLs for CSS files in Salesforce resemble this:

`/sCSS/25.0/sprites/1344400715000/Theme3/default/gc/elements.css`

What does the `1344400715000` refer to, and is there a way to expose that value via global variables? I know that I could find it retroactively with this javascript:

```
var reg = /\d{13}/;
var cssurl = document.getElementsByTagName('link')[0];
var mystery = cssurl.match(reg)[0]

```

But I'd love a way to find it proactively.