[Rails] A number (id?) is added after css/js tags like style.css?1154009736

[Mathieu Chappuis]

Dears,

My Ror setup works.. but I can't guess why

<%= stylesheet_link_tag 'style' , :media=> 'screen'%>

is rended as

<link href="/stylesheets/style.css?1154009736" media="screen"
rel="Stylesheet" type="text/css" />

What is that number.. any usage ??

Or I misconfigured something ?

Thanks