.button { background: url(../Images/button.png); }

Problem: for performance reason all static content has expiration headers and is cached by browser. When image changes user must refresh cache (Ctrl+F5 in IE). I want images to be cached, but when necessary they must be automatically reloaded.

Question: is next approach 'valid'?

.button {
    background: url(../Images/button.png?v=1234);
}

where v=1234 is version of my site. I do not know whether it is 100% valid to write such things in CSS and I do want browsers to still cache images if version is the same. Do all modern browsers correctly cache data with URL parameters part?

Thanks.

css caching
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