D. Glossary

• [Batch]An accumulation of data brought together for processing or transmission, usually unattended. Less formally, the processing of such data, as opposed to on-line processing where an user is present to respond interactively, one record at a time.
• [Dataset]An unit of data storage and retrieval consisting of one or more data records. Outside of the IBM mainframe environment, people call them files. Dataset can be partioned (i.e. containing multiple files) or sequential (i.e. containing only data).
• [DBCS]stands for Double Byte Character Set. A mainframe way of coding non-latin character sets (i.e. chinese, japanese, etc).
• [DTD]Document Type Definition. This is a specific markup language, written using SGML.
• [ISPF/PDF]ISPF/Program Development Facility. ISPF facility providing access to application development services for end-users and programmers. Incorporates C and REXX programming support, and some support for programmable workstations.
• [GUI]stands for Graphical User Interface. A GUI application must be installed on each PC and makes extensive use of the mouse. By opposition, TUI is Text User Interface. A TUI application needs a connection program called an emulator and use only the keyboard to input data. BUI stands for Browser User Interface. A BUI program is an intranet or extranet application.
• [HLQ]High Level Qualifier. The left part of a dataset name.
• [IVP]Installation Verification Procedure. A set of tests to check if a product was correctly installed.
• [JCL]Job Control Language. The language used to describe the steps of a batch job (files to be used, programs to be run, etc). A generic term, hijacked by IBM to refer to the batch control languages for its System/360 operating systems. Then, as now, z/OS and VSE/ESA JCL is a clumsy and cumbersome system that is hard to learn, full of inconsistencies, and avoided by anyone with an iota of common sense and access to an alternative. The only excuse for it comes from one of the original OS/360 developers: they ran out of time to build a JCL interpreter, so just used the Assembler macro processor, and built a language (JCL) around it.
• [Mainframe]Mainframes used to be defined by their size, and they can still fill a room, cost millions, and support thousands of users. But now a mainframe can also run on a laptop and support two users. So today's mainframes are best defined by their operating systems: Unix and Linux, and IBM's z/OS, OS/390, MVS, VM, and VSE. Mainframes combine four important features:
  • Reliable single-thread performance, which is essential for reasonable operations against a database.
  • Maximum I/O connectivity, which means mainframes excel at providing for huge disk farms.
  • Maximum I/O bandwidth, so connections between drives and processors have few choke-points.
  • Reliability-mainframes often allow for "graceful degradation" and service while the system is running.
• [Member]A file of a partitioned dataset.
• [MVS]Multiple Virtual Storage. In z/OSs long history, MVS has the honor of being its name for the longest period: about two decades. Admittedly, it had many suffixes during those years: MVS/SP, MVS/370, MVS/XA and MVS/ESA. Many users believed that MVS stood for Man Versus System.
• [OS/390]The replacement for MVS/ESA announced at the end of 1995. It was an attempt to repackage MVS in a way that allowed IBM to offer attractive pricing at the lower levels, encourage developers to write applications in a shorter period of time, and generally improve the image of an operating system that is still largely identified with big iron and huge IT budgets. It also reduced IBMs testing costs dramatically because there was no longer a need to test every combination of supported releases of what were now components instead of separate system software products. This approach was first tested with DFSMS three and a half years earlier. In the longer term, OS/390 shielded MVS behind a layer of middleware that disguised many of the proprietary functions of MVS and provided users with common services across all the major IBM platforms. Replaced by z/OS on October 3, 2000, along with the introduction of eserver, including a complete line of mainframes called zSeries 900. Version 2 Release 10 was the last release of OS/390 and first became available September 29, 2000.
• [Panel]IBM speak for screen layout.
• [REXX]Restructured EXtended eXecutor language. A command procedure programming language which was initially available on z/VM only, replacing EXEC and EXEC2, but later became an SAA standard. Although SAA is a distant memory, REXX availability in z/OS TSO has seen it replace CLIST as the tool of choice, especially given the fact that TSO, and therefore REXX, can be run in batch. REXX is an effective programming language in its own right with powerful string processing facilities and is used to drive certain program products, notably GDDM. REXX is also available in VSE/ESA, AIX1, OS/2, Linux and Windows. Although normally interpretive, a REXX compiler and library is available for z/OS and z/VM. REXX for CICS is available for z/OS and VSE/ESA; it consists of REXX Development System and REXX Development System. Object REXX is available for Windows, OS/2, AIX, and Linux for Intel and zSeries 900.
• [Shell]Generic term with a lot of different meanings. Early Internet service often involved an interface, called a Shell, on a host computer, rather than a direct connection to the Internet. And there was the IBM DOS Shell, a menu driven interface to basic PC-DOS functionality. Shell is also widely used in the expert systems and Unix communities, to mean software providing a skeleton which can be customized to produce a specific application.
• [TSO]Time Sharing Option. These days, everyone just says TSO when they mean TSO/E. Back in the 1980s, TSO was included with MVS/XA and you had to pay extra for TSO/E. Well worth the money given that TSO left you stranded below the 16MB line.
• [TSO/E]Time Sharing Option/Extensions. An element of z/OS that provides an on-line interactive environment for programmers and users. Best known for the ISPF/PDF environment that runs on TSO/E. Can also be used to test batch programs.
• [Two's] 
• [complement]is a method of signifying negative numbers in binary. It is also an operation which may be applied to positive binary values in order to perform subtraction using the method of complements, effectively allowing subtraction of one binary number from another using only the addition operation.
• [XUL]The XML User Interface Language (XUL) is a markup language for describing user interfaces. With XUL you can create rich, sophisticated cross-platform web applications easily.