diff --git a/cpdfcommand.ml b/cpdfcommand.ml
index db6e65f..f6df9c1 100644
--- a/cpdfcommand.ml
+++ b/cpdfcommand.ml
@@ -220,6 +220,7 @@ type op =
   | ExtractStream of int
   | PrintObj of int
   | Verify of string
+  | MarkAs of string
 
 let string_of_op = function
   | PrintFontEncoding _ -> "PrintFontEncoding"
@@ -363,6 +364,7 @@ let string_of_op = function
   | ExtractStream _ -> "ExtractStream"
   | PrintObj _ -> "PrintObj"
   | Verify _ -> "Verify"
+  | MarkAs _ -> "MarkAs"
 
 (* Inputs: filename, pagespec. *)
 type input_kind = 
@@ -883,7 +885,7 @@ let banned banlist = function
   | AddPageLabels | RemovePageLabels | OutputJSON | OCGCoalesce
   | OCGRename | OCGList | OCGOrderAll | PrintFontEncoding _ | TableOfContents | Typeset _ | Composition _
   | TextWidth _ | SetAnnotations _ | CopyAnnotations _ | ExtractStream _ | PrintObj _
-  | Verify _
+  | Verify _ | MarkAs _ 
      -> false (* Always allowed *)
   (* Combine pages is not allowed because we would not know where to get the
   -recrypt from -- the first or second file? *)
@@ -2807,6 +2809,7 @@ and specs =
    ("-obj", Arg.Int setprintobj, "Print object");
    ("-json", Arg.Unit (fun () -> args.format_json <- true), "Format output as JSON");
    ("-verify", Arg.String (fun s -> setop (Verify s) ()), "Verify conformance to a standard");
+   ("-marks-as", Arg.String (fun s -> setop (MarkAs s) ()), "Mark as conforming to a standard");
    (* These items are undocumented *)
    ("-debug", Arg.Unit setdebug, "");
    ("-debug-crypt", Arg.Unit (fun () -> args.debugcrypt <- true), "");
@@ -4442,6 +4445,14 @@ let go () =
               else Cpdfua.test_matterhorn_print pdf
       | _ -> error "Unknown verification type."
       end
+  | Some (MarkAs standard) ->
+      begin match standard with
+      | "PDF/UA-1" ->
+          let pdf = get_single_pdf args.op false in
+            Cpdfua.mark pdf;
+            write_pdf false pdf
+      | _ -> error "Unknown standard"
+      end
 
 (* Advise the user if a combination of command line flags makes little sense,
 or error out if it make no sense at all. *)
diff --git a/cpdfmetadata.ml b/cpdfmetadata.ml
index 0a72241..34e0e9e 100644
--- a/cpdfmetadata.ml
+++ b/cpdfmetadata.ml
@@ -56,6 +56,11 @@ let xmp_template =
 
 <?xpacket end='r'?>|}
 
+let pdfua_marker =
+{|<rdf:Description rdf:about="" xmlns:pdfuaid="http://www.aiim.org/pdfua/ns/id/">
+    <pdfuaid:part>1</pdfuaid:part>
+  </rdf:Description>"|}
+
 (* Set or replace metadata *)
 let set_metadata_from_bytes keepversion data pdf =
   let metadata_stream =
diff --git a/cpdfua.ml b/cpdfua.ml
index ceba5e6..cc19c56 100644
--- a/cpdfua.ml
+++ b/cpdfua.ml
@@ -230,3 +230,5 @@ let test_matterhorn_json pdf =
       (fun (name, error, section, extra) ->
         `Assoc [("name", `String name); ("section", `String section); ("error", `String error); ("extra", extra)])
       (test_matterhorn pdf))
+
+let mark pdf = ()
diff --git a/cpdfua.mli b/cpdfua.mli
index b10d9b6..4ca88dd 100644
--- a/cpdfua.mli
+++ b/cpdfua.mli
@@ -2,3 +2,5 @@
 val test_matterhorn_print : Pdf.t -> unit
 
 val test_matterhorn_json : Pdf.t -> Cpdfyojson.Safe.t
+
+val mark : Pdf.t -> unit