Bash (zsh) script syntax issue : I've honestly worn out my keyboard on this one... what does the (N) term in the following script segment mean? (from oh-my-zsh.sh):

    for config_file ($ZSH_CUSTOM/*.zsh**(N)**); do
      source $config_file
    done

I ask because .zsh files in $ZSH_CUSTOM directory aren't getting sourced. Thanks for any insights!