diff --git a/src/config.ml b/src/config.ml
index 08fff141..5fbe59df 100644
--- a/src/config.ml
+++ b/src/config.ml
@@ -1,7 +1,10 @@
 (* https://docs.taler.net/manpages/taler-exchange.conf.5.html#exchange-options *)
 (* TODO
    - generate `config.ml` from config file (virtual module)?
+   - parse config file format
    - no relative path *)
+(* TODO default config: use relevant duration, all set to 1 year for now *)
+
 
 let default_lang = "en"
 let default_encoding : [< `Identity | `DEFLATE | `Gzip ] = `Identity
@@ -37,8 +40,7 @@ let currency_round_unit = { currency= `Eur; value= 0; fraction= 1 }
 let value_to_string v =
   Fmt.str "%s:%d.%d" (currency_to_string v.currency) v.value v.fraction
 
-(* todo: use relevant duration, all set to 1 year for now *)
-
+(* https://docs.taler.net/manpages/taler-exchange.conf.5.html#exchange-coin-options *)
 module Coin = struct
   (* How much is the coin worth, the format is CURRENCY:VALUE.FRACTION. For
      example, a 10 cent piece is “EUR:0.10”. *)