are always big endian, regardless of the endianness of the underlying hardware platform. On little endian servers with x86 processors, the compilers do a byte swap before reading or writing values to memory to transform the data to or from the native little endian format. Command Macro Language VOS has a fairly complete command macro language which can be used to create menu systems, automate tasks etc. VOS command macros accept arguments on the command-line or via a user interface "form". Arguments are defined at the beginning of the command macro in a "parameters" section. The language supports a range of statements, including if/then/else, boolean operations, "while" loops, "goto" and excellent error reporting. The command macro language can be executed in interactive and non-interactive (batch or started process) modes. It can be used to automate programs, capturing prompts and sending appropriate responses. This has led Stratus to limit the capabilities of the command macro language. The macro language lacks support for user-defined functions and does not easily support include files. The string handling is prone to errors, especially with embedded control characters. Overview VOS was coded mainly in PL/I with a small amount of assembly language before it was migrated to ftServer series. As of 1991, the system was written in PL/I and C, with only 3% in assembly. Its overall structure has much in common with Multics, and many of the system's features can be traced back to Multics to varying degrees. The system exposes a number of fundamental abstractions to the software designer or programmer, most notable being Processes Devices Hard Disks Various IPC mechanisms Tasks A process is the scheduled entity in VOS and each process has a set of attributes that govern how it is manipulated by the system. For example, processes have a user name and process name. The former is used by VOS to determine the process's access rights to external devices and items with the file system. Of fundamental significance is a process's privileged flag, which is a binary attribute. Privileged processes may perform privileged operations. This mechanism is used to restrict certain potentially powerful operations that can have system wide consequences (e.g. shutting down the system, dismounting a hard disk etc.). Distribution VOS is distributed only by Stratus Technologies. The distribution media is a 3.5 mm DAT tape for Continuum, and an SDLT tape for early V Series platforms. As of OpenVOS