In the comments for get_bookmarks(), the parameters 'include' and 'exclude' are described as being for "categories", but I'm pretty sure what's being in-/ex-cluded is link_id(s).
If so, then in file wp-includes/bookmark.php on lines 104-107:
* 'include' - Default is empty string (string). Include other categories
* separated by commas.
* 'exclude' - Default is empty string (string). Exclude other categories
* separated by commas.
It should probably be:
"...Include bookmark ID(s) separated by commas." And "Exclude bookmark ID(s)...".