* Install python-pip
user@host ~/Documents/git/open5gs/lib/gtp/support$ \
    sudo apt-get install python-pip

* Install python-docx
user@host ~/Documents/git/open5gs/lib/gtp/support$ \
    sudo pip install python-docx

* Change the format of standard specification 
  from 24301-d80.doc to 24301-d80.docx 
  using Microsoft Office 2007+

* Generate Message support files
user@host ~/Documents/git/open5gs/lib/s1ap/support$ \
    python nas-message.py -f 24501-g41.docx -o ..