diff --git includes/file.inc includes/file.inc
index 8f266e1..0845a9d 100644
--- includes/file.inc
+++ includes/file.inc
@@ -461,7 +461,7 @@ function file_space_used($uid = NULL) {
  * @param $source
  *   A string specifying the name of the upload field to save.
  * @param $validators
- *   An optional, associative array of callback functions used to validate the
+ *   (optional) An associative array of callback functions used to validate the
  *   file. The keys are function names and the values arrays of callback
  *   parameters which will be passed in after the user and file objects. The
  *   functions should return an array of error messages, an empty array
@@ -471,9 +471,12 @@ function file_space_used($uid = NULL) {
  *   A string containing the directory $source should be copied to. If this is
  *   not provided or is not writable, the temporary directory will be used.
  * @param $replace
- *   A boolean indicating whether an existing file of the same name in the
- *   destination directory should overwritten. A false value will generate a
- *   new, unique filename in the destination directory.
+ *   Replace behavior when the destination file already exists:
+ *   - FILE_EXISTS_REPLACE: Replace the existing file.
+ *   - FILE_EXISTS_RENAME: Append _{incrementing number} until the filename
+ *     is unique.
+ *   - FILE_EXISTS_ERROR: Do nothing and return FALSE.
+ *
  * @return
  *   An object containing the file information, or 0 in the event of an error.
  */