These releases could be either a SB (Safety Bulletin) a TB (Technical Bulletin) or a PB which is a (Parts Bulletin).
A Safety Bulletin is for Safety related issue and the end users should up-date and acted on ASAP.
A Technical Bulletin is for a technical up-date or improvement and they are recommendation for the end user to add to their products, i.e. in this LS171NP.
A Parts Bulletin is for a parts related up-date, usually to up-date parts books etc.
Please find attached your first TB release, no need to worry as this does not affect the LS171NP at Thai Kali. We release these SB, TB, & PB's out to internal personnel first, then they can get released out to our customers. Everyone should keep a record of these with the individual machine files.