1) I suppose there's a bug in \prop_map_function_aux:NNn. Here is the diff: --- l3prop.dtx.orig 2006-12-12 13:28:27.000000000 +0100 +++ l3prop.dtx 2007-05-05 22:04:43.000000000 +0200 @@ -665,7 +665,7 @@ \exp_after:NN #2 \prop_use:N #1 \q_nil \q_no_value \q_stop } \def_new:Npn \prop_map_function_aux:NNn #1#2#3{ - \if_meaning:NN \q_nil #1 + \if_meaning:NN \q_nil #2 \exp_after:NN \prop_map_break:w \fi: #1#2{#3} 2) I have no idea how to use \prop_map_inline:NN. Can someone show me? There seems to be a missing \prop_map_function:N. Ciao Andreas