Service packs are cumulative.
This means that the bugs fixed in a service pack are also fixed in subsequent service packs. Click the Qxxxxxx number that precedes the title of the bug fix to view the article about that bug. 6 Windows NT Service Pack 6a was released to fix specific issues in Service Pack 6. Q246009 Windows NT 4.0 Service Pack 6a Available Windows NT 4.0 Service Pack 6a also contains the SP6 fixes described below. According to GMT, Not Local Time Zone Q217763 File Access Vulnerability in Personal Web Server Q218880 ASP Request.