thx Nicolas for the answer.

im still having issues getting this to work

here is my modified example

**** main i3 conf
     :PROPERTIES:
     :ID:       f17b5518-2695-4484-a958-2fc7b8aa2479
     :header-args: :tangle   ~/.i3/config
     :END:
mod is win key and mod1 is alt key in below config
***** General definitions
      :PROPERTIES:
      :ID:       97fcf6e4-a81d-4fe8-badc-6a9b48668ec2
      :END:
#+BEGIN_SRC conf
# i3 general settings
#set variable names
set $mod Mod4
# Use Mouse+$mod to drag floating windows to their wanted position
floating_modifier $mod
#+END_SRC


yet when i try to tangle recursively i get:

org-babel-execute-src-block: No org-babel-execute function for conf!

is my syntax wrong?

best and thx again

Z