diff --git a/cpdfaddtext.ml b/cpdfaddtext.ml
index 80848de..d0fdf38 100644
--- a/cpdfaddtext.ml
+++ b/cpdfaddtext.ml
@@ -2,7 +2,7 @@
 open Pdfutil
 open Cpdferror
 
-type color =
+type colour =
   Grey of float
 | RGB of float * float * float
 | CYMK of float * float * float * float
diff --git a/cpdfaddtext.mli b/cpdfaddtext.mli
index 8e94e51..5388529 100644
--- a/cpdfaddtext.mli
+++ b/cpdfaddtext.mli
@@ -1,13 +1,16 @@
 (** Adding text *)
 
-type color =
+(** Colours *)
+type colour =
   Grey of float
 | RGB of float * float * float
 | CYMK of float * float * float * float
 
-val colour_op : color -> Pdfops.t
+(** Build a colour operation for filling with the given colour. *)
+val colour_op : colour -> Pdfops.t
 
-val colour_op_stroke : color -> Pdfops.t
+(** Build a colour operation for filing with the given colour *)
+val colour_op_stroke : colour -> Pdfops.t
 
 (** Justification of multiline text *)
 type justification =
@@ -26,7 +29,7 @@ val addtexts :
     Cpdfembed.cpdffont -> (*font*)
     int -> (* bates number *)
     int option -> (* bates padding width *)
-    color -> (*colour*)
+    colour -> (*colour*)
     Cpdfposition.position -> (*position*)
     float -> (*linespacing*)
     float -> (*fontsize*)
@@ -45,12 +48,11 @@ val addtexts :
     Pdf.t ->(*pdf*)
     Pdf.t
 
-
 (** Add a rectangle to the given pages. [addrectangle fast (w, h) colour outline linewidth opacity position relative_to_cropbox underneath range pdf]. *) 
 val addrectangle :
     bool ->
     float * float ->
-    color ->
+    colour ->
     bool ->
     float ->
     float ->
diff --git a/cpdfchop.mli b/cpdfchop.mli
index 5154650..a01ef29 100644
--- a/cpdfchop.mli
+++ b/cpdfchop.mli
@@ -1,6 +1,7 @@
 (** Chop *)
 
-(** Chop a page into pieces. *)
+(** Chop pages in the given range into pieces. *)
 val chop : x:int -> y:int -> columns:bool -> btt:bool -> rtl:bool -> Pdf.t -> int list -> Pdf.t
 
+(** Chop a page in the given range horizontally or vertically. *)
 val chop_hv : is_h:bool -> line:float -> columns:bool -> Pdf.t -> int list -> Pdf.t
diff --git a/cpdfcommand.ml b/cpdfcommand.ml
index 07b96b9..5797654 100644
--- a/cpdfcommand.ml
+++ b/cpdfcommand.ml
@@ -430,7 +430,7 @@ type args =
    mutable fontencoding : Pdftext.encoding;
    mutable fontsize : float;
    mutable embedstd14 : string option;
-   mutable color : Cpdfaddtext.color;
+   mutable color : Cpdfaddtext.colour;
    mutable opacity : float;
    mutable position : Cpdfposition.position;
    mutable underneath : bool;
@@ -1201,7 +1201,7 @@ let setaddtext s =
   setop (AddText s) ()
 
 let setcolor s =
-  args.color <- Cpdfdrawcontrol.parse_color s
+  args.color <- Cpdfdrawcontrol.parse_colour s
 
 let setopacity o =
   args.opacity <- o
diff --git a/cpdfcomposition.mli b/cpdfcomposition.mli
index 4dcd6c8..a8496fd 100644
--- a/cpdfcomposition.mli
+++ b/cpdfcomposition.mli
@@ -1,7 +1,9 @@
 (** Show composition of a PDF *)
 
 (** [show_composition filesize json pdf] prints the composition of a document to
-   Standard Output. *)
+Standard Output. *)
 val show_composition : int -> bool -> Pdf.t -> unit
 
+(** [show_composition_json_blob filesize json pdf] returns the composition of a
+document in JSON format. *)
 val show_composition_json_blob : int -> Pdf.t -> Pdfio.bytes
diff --git a/cpdfdrawcontrol.ml b/cpdfdrawcontrol.ml
index e13c965..9eba079 100644
--- a/cpdfdrawcontrol.ml
+++ b/cpdfdrawcontrol.ml
@@ -63,7 +63,7 @@ let pop () =
 
 let readfloats s = map float_of_string (String.split_on_char ' ' s)
 
-let parse_color s =
+let parse_colour s =
   match lookup (String.lowercase_ascii s) Cpdfcolours.colours with
   | Some c ->
       let r = float_of_int ((c land 0xFF0000) lsr 16) /. 255. in
@@ -83,7 +83,7 @@ let parse_color s =
         | _ -> error "Bad color"
 
 let col_of_string s =  
-  match parse_color s with
+  match parse_colour s with
   | Cpdfaddtext.RGB (r, g, b) -> Cpdfdraw.RGB (r, g, b)
   | Cpdfaddtext.Grey g -> Cpdfdraw.Grey g
   | Cpdfaddtext.CYMK (c, y, m, k) -> Cpdfdraw.CYMK (c, y, m, k)
diff --git a/cpdfdrawcontrol.mli b/cpdfdrawcontrol.mli
index 2ead90b..f918733 100644
--- a/cpdfdrawcontrol.mli
+++ b/cpdfdrawcontrol.mli
@@ -1,3 +1,5 @@
+(** Cpdfcommand draw control *)
+
 val embed_font : (unit -> Cpdfembed.cpdffont) ref
 val getfontname : (unit -> string) ref
 val getfontsize : (unit -> float) ref
@@ -11,7 +13,7 @@ val loadttfseparate : string -> string -> unit
 val fontpack_initialised : bool ref
 val drawops : (string * Cpdfdraw.drawops list) list ref
 val addop : Cpdfdraw.drawops -> unit
-val parse_color : string -> Cpdfaddtext.color
+val parse_colour : string -> Cpdfaddtext.colour
 val addrect : string -> unit
 val addto : string -> unit
 val addline : string -> unit
@@ -64,3 +66,6 @@ val addnewline : unit -> unit
 val add_default_fontpack : string -> unit
 val addtext : string -> unit
 val addspecialtext : string -> unit
+
+(** This the beginnings of separation between cpdfcommand and cpdfdraw when
+    drawing, for use in cpdflib. It is presently undocumented. *)
diff --git a/cpdfimage.mli b/cpdfimage.mli
index 85b32a6..66fcb14 100644
--- a/cpdfimage.mli
+++ b/cpdfimage.mli
@@ -11,6 +11,7 @@ val extract_images :
 (** Report image resolutions. *)        
 val image_resolution : Pdf.t -> int list -> float -> (int * string * int * int * float * float * int) list
 
+(** Report image resolution data in JSON format *)
 val image_resolution_json : Pdf.t -> int list -> float -> Pdfio.bytes
 
 (** List images in JSON format *)
diff --git a/cpdfmetadata.mli b/cpdfmetadata.mli
index 5d4c6a1..314e68e 100644
--- a/cpdfmetadata.mli
+++ b/cpdfmetadata.mli
@@ -80,7 +80,7 @@ val set_metadata_date : Pdf.t -> string -> Pdf.t
 (** Expands the date ["now"] to the date now. Leaves any other string alone. *) 
 val expand_date : string -> string
 
-(** / **)
+(**/**)
 val get_catalog_item : string -> Pdf.t -> string
 
 val get_viewer_pref_item : string -> Pdf.t -> string
diff --git a/cpdfpage.mli b/cpdfpage.mli
index cdc9e47..c9917d9 100644
--- a/cpdfpage.mli
+++ b/cpdfpage.mli
@@ -25,6 +25,8 @@ val hard_box : Pdf.t -> int list -> string -> bool -> bool -> Pdf.t
 for all pages in pdf. *)
 val shift_pdf : ?fast:bool -> (float * float) list -> Pdf.t -> int list -> Pdf.t
 
+(** Shift a PDF's boxes in x and y (in pts) in the given pages. List of (x, y)
+pairs is for all pages in pdf. *)
 val shift_boxes : (float * float) list -> Pdf.t -> int list -> Pdf.t
 
 (** Change a page's media box so its minimum x and y are 0, making other
diff --git a/cpdftweak.mli b/cpdftweak.mli
index bd32c0d..6db705b 100644
--- a/cpdftweak.mli
+++ b/cpdftweak.mli
@@ -4,13 +4,13 @@
 val thinlines : int list -> float -> Pdf.t -> Pdf.t
 
 (** Make all text on certain pages black. *)
-val blacktext : Cpdfaddtext.color -> int list -> Pdf.t -> Pdf.t
+val blacktext : Cpdfaddtext.colour -> int list -> Pdf.t -> Pdf.t
 
 (** Make all lines on certain pages black. *)
-val blacklines : Cpdfaddtext.color -> int list -> Pdf.t -> Pdf.t
+val blacklines : Cpdfaddtext.colour -> int list -> Pdf.t -> Pdf.t
 
 (** Make all fills on certain pages black. *)
-val blackfills : Cpdfaddtext.color -> int list -> Pdf.t -> Pdf.t
+val blackfills : Cpdfaddtext.colour -> int list -> Pdf.t -> Pdf.t
 
 (** Append page content. *)
 val append_page_content : string -> bool -> bool -> int list -> Pdf.t -> Pdf.t