If you are writing to multiple CSS files, you can give each css:rule or css:media element a stream attribute; the value of this attribute can be #all or a space-separated list of identifiers (as for the HTML class attribute); the corresponding CSS rules are generated to replace a css:stream element having a name attribute with the same value; the stream name can also be passed as a parameter to the css:gather template which gathers the styles from where they occur in the stylesheet into one place. This is not currently implemented, but is planned.