What does SOS in SQL Server stand for? I am reading SQL Server 2012 Internals book now. There are several phrases with SOS acronym, such as "SOS Scheduler" (in chapter about the scheduler), "SOS Memory node" (in chapter about the free buffer list and the lazywriter). But I can't find the meaning anywhere.
It's actually usually referred to as SQLOS and it means SQL Server Operating System.


Details in this series


Also it can be found referenced in documentation in some places, e.g. here:


  [...] associated with the SQL Server Operating System (SQLOS). The SQLOS is responsible for managing operating system resources that are specific to SQL Server.