Sourcetype picture = {src : string;height : float;middle : bool;
} Sourcetype line = {top : float;height : float;baseline : float;fragments : fragment list;anchors : string list;
} Sourcetype marker = | Bullet| Number of int
Sourcetype unit_ = {space : float;width : float;
} Sourcetype breaker = measure:float -> unit_ array -> (int * int) list Sourceval first_baseline : box -> float option