On Jan 19, 2012, at 7:32 AM, Romain Diss wrote:

Unfortunately, I have now another problem which I didn't notice before because the \encl{} error didn't let me go to the end of the tex processing. The following minimal example do not compile:

% example \usemodule[letter] \startletter \input tufte \stopletter % end

Instead, I get the following error message:

! Missing number, treated as zero.

system > tex > error on line 100 in file letter.tex: Missing number, treated as zero ...

<to be read again> \relax \pack_layers_set_content ..._pack_layers_x \relax \d_pack_layers_y_position ... \pack_layers_set_finish ...layers_set_content {#1} \fi \fi \else \writestatus... \correspondence_layer_place ...dence_layer_direct \fi \else \ifodd \c_corres... \executedefinedoverlay ...dp \the \everyoverlay #2 \else \lower \d_framed_tar... \pack_framed_process_background_indeed_external ... \else \kern -\framedbackgr... ... l.7 \stopletter

Any idea which could help me?

Does your file start with a byte order mark (BOM)?