diff --git a/elements.ml b/elements.ml
index a2877fb..846b0f0 100644
--- a/elements.ml
+++ b/elements.ml
@@ -1,13 +1,23 @@
 module Opts = struct
 	open Arg
 
-	type lasttype = NAME | SYMB
+	type lasttype = NAME | SYMB | NUMB
 
+	(** Positional arguments search based on the last type searched. *)
 	let ltype = ref NAME
+
+	(** Json file that generates the Sqlite3 database. *)
 	let jsonf = ref ""
+
+	(** Limit the amount of matches. *)
 	let maxmatch = ref 3
+
+	(** Lists to search. *)
+
 	let match_name : string list ref = ref []
 	let match_symb : string list ref = ref []
+	let match_numb : int list ref = ref []
+
 	let dbfile = ref "elements.sqlite3"
 
 	let add_name s =
@@ -16,9 +26,13 @@ module Opts = struct
 	let add_symb s =
 		match_symb := s::!match_symb;
 		ltype := SYMB
+	let add_numb i =
+		match_numb := i::!match_numb;
+		ltype := NUMB
 	let add_def s = match !ltype with
 	| NAME -> add_name s
 	| SYMB -> add_symb s
+	| NUMB -> add_numb (int_of_string s)
 
 	let msg = "Periodic table search\n\
 		elements -gendb file [-dbfile outfile]\n\
@@ -35,7 +49,8 @@ module Opts = struct
 	"-maxmatch", Set_int maxmatch, "Limit the amount of matches (def. 3)";
 	"-dbfile", String (setfile "-dbfile" dbfile), "Set the DB filename";
 	"-name", String add_name, "Search by name (default)";
-	"-symb", String add_symb, "Search by symbol"
+	"-symb", String add_symb, "Search by symbol";
+	"-num", Int add_numb, "Search by atomic number"
 	]
 
 	let exec() = parse spec add_def msg
@@ -44,7 +59,7 @@ end
 let () = Opts.exec()
 
 let db = Sqlite3.db_open !Opts.dbfile
-if !Opts.jsonf <> "" then
+let _ = if !Opts.jsonf <> "" then
 	Makedb.makedb db (if !Opts.jsonf = "-" then
 			Yojson.Basic.from_channel stdin
 		 else