* @param ParserOptions $options
* @param bool $linestart
* @param bool $clearState
- * @param int|null $revid Number to pass in {{REVISIONID}}
+ * @param int|null $revid ID of the revision being rendered. This is used to render
+ * REVISION* magic words. 0 means that any current revision will be used. Null means
+ * that {{REVISIONID}}/{{REVISIONUSER}} will be empty and {{REVISIONTIMESTAMP}} will
+ * use the current timestamp.
* @return ParserOutput A ParserOutput
* @return-taint escaped
*/