diff --git a/src/adl_support/filters.clj b/src/adl_support/filters.clj
new file mode 100644
index 0000000..72f3576
--- /dev/null
+++ b/src/adl_support/filters.clj
@@ -0,0 +1,63 @@
+(ns adl-support.filters
+    (:require [clojure.string :as s]
+              [selmer.filters :as f]
+              [selmer.parser :as p]))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; adl-support.filters: selmer filters required by ADL selmer views.
+;;;;
+;;;; This program is free software; you can redistribute it and/or
+;;;; modify it under the terms of the MIT-style licence provided; see LICENSE.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;;; License for more details.
+;;;;
+;;;; Copyright (C) 2018 Simon Brooke
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+
+(def *default-international-dialing-prefix*
+  "The international dialing prefix to use, if none is specified."
+  "44")
+
+(defn telephone
+  "If `arg` is, or appears to be, a valid telephone number, convert it into
+  a `tel:` link, else leave it be."
+  [^String arg]
+  (let [number
+        (s/replace
+         (s/replace
+          arg
+          #"^0"
+          (str "+" *default-international-dialing-prefix* "-"))
+         #"\s+" "-")]
+    (if (re-matches #"[0-9 +-]*" arg)
+      [:safe (str "<a href='tel:" number "'>" arg "</a>")]
+      arg)))
+
+
+;; (telephone "07768 130255")
+;; (telephone "Freddy")
+
+(defn email
+  "If `arg` is, or appears to be, a valid email address, convert it into
+  a `mailto:` link, else leave it be."
+  [^String arg]
+  (if (re-matches #"^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,6}$" arg)
+    [:safe (str "<a href='mailto:" arg "'>" arg "</a>")]
+    arg))
+
+
+;; (email "simon@journeyman.cc")
+;; (email "simon@journeyman")
+;; (email "simon@journeyman.cc.")
+
+(f/add-filter! :telephone telephone)
+
+(f/add-filter! :email email)
+
+;; (p/render "{{p|telephone}}" {:p "07768 130255"})
diff --git a/src/adl_support/forms_support.clj b/src/adl_support/forms_support.clj
index d51ffa7..fb7d0f1 100644
--- a/src/adl_support/forms_support.clj
+++ b/src/adl_support/forms_support.clj
@@ -98,6 +98,8 @@
   "Params for insertion into the database must have keys for all fields in the
   insert query, even if the value of some of those keys is nil. Massage these
   `params` to have a value for each field in these `fields`."
+  ;; TODO: should intelligently handle dates and times, but that might imply
+  ;; access to ADL at runtime!
   [params fields]
   `(merge
     (reduce merge {} (map #(hash-map (keyword %) nil) ~fields))