S

SACL (system access control list)

A part of the Windows NT security descriptor for an object, used to maintain per object auditing information. See also security descriptor, ACE, and ACL.

SAP (service access point)

security descriptor

A data structure used to hold per-object security information, including the object’s owner, group, protection attributes, and audit information. See also ACE, ACL, SACL, and SID.

SID (security identifier)

A value, unique across time and space, that identifies a process in the Security system. SIDs can either identify an individual process, usually containing a user’s logon identifier, or a group of processes.

SMP machine (symmetric multiprocessor machine)

See multiprocessor machine.

SNAP (sub-network access protocol)

SONIC (systems-oriented network interface controller)

SONIC or Sonic

spin lock

A spin lock is a low-level, synchronization mechanism defined by the Windows NT Kernel. A driver or any other kernel-mode component that runs at raised IRQL can use a spin lock to synchronize access to a shared resource, particularly in a multiprocessor machine.

When one routine holds a spin lock, a second routine running on another processor cannot access the resource protected by that spin lock until it acquires the lock. While a routine attempts to acquire a spin lock, it cannot carry out other operations (it spins) until the lock has been acquired.

Operations involving system-defined spin locks are IRQL-specific to help prevent deadlocks: an interrupt spin lock can only be acquired while executing at a DIRQL of the associated interrupt object(s); an executive spin lock can only be acquired while executing at the highest IRQL (usually DISPATCH_LEVEL) of any routine that can acquire that executive spin lock.

STREAMS

A network communication environment based on UNIX STREAMS. Windows NT STREAMS facilitates the porting of existing stream transport drivers to Windows NT.

SVR4

System V, Release 4 (UNIX).