i apologize for my late answer,

i wrote a long draft mail with code yesterday for answering but it is too long i think to be send and will confuse everyone,

i'm testing a lot of answer,perhaps modifying my goals too!,

and try to summarize all that,not easy.....

for now my goal change a little bit,it is already :

"i need a procedure or macro that define a variable only if it is not bind and if it is just set! it" i will just add but define locally in the block or nested code not globally and for now that is the hard thing, i see some good solution but which sometimes bind the variable globally in the (current-module) and that is not what i want.

I'm conducting tests still......

Damien