24/7

24 hours a day, seven days a week

Spell out or replace with phrases such as all the time or all day, every day. For repeated mentions or in contexts where the abbreviation is standard, use the abbreviation after first mention.

AC

alternating current

Don’t spell out.

ACL

access control list

AD

Active Directory

Don’t use either the abbreviation or the expanded form as a stand-alone term. Use Active Directory Domain Services (AD DS) instead.

ADO

ActiveX Data Objects

Not Active Data Objects.

ADSL

asymmetric digital subscriber line

Not asynchronous digital subscriber line.

AM/FM

amplitude modulation/frequency modulation

Don’t spell out.

AJAX

Asynchronous JavaScript and XML

ALM

application lifecycle management

Abbreviation for application lifecycle management. For repeated mention of application lifecycle management, spell out ALM on first mention. On subsequent mention, use just ALM or lifecycle management. Capitalize as Application Lifecycle Management when referring to Visual Studio ALM.

ANSI

American National Standards Institute

Spell out only to refer to the organization itself. Don’t spell out when referring to ANSI standards or text format.

API

application programming interface

Not application program interface. Don’t use to refer to individual programming elements. Don’t use the redundant term API set.

APPC

Advanced Program-to-Program Communications

Note capitalization and hyphenation.

ASCII

American Standard Code for Information Interchange

Don’t spell out.

ASP

When referring to Active Server Pages, don’t use ASP and ASP.NET interchangeably, and don’t spell out in the context of ASP.NET. Otherwise, spell out if the context is not clear.

When referring to application service provider, always spell out on first mention.

AVI

Audio Video Interleaved

Don’t spell out. If the term is not familiar to your audience, use a more generic term such as movie.

B2B

business-to-business

Spell out unless the abbreviation is familiar to your audience.

B2C

business-to-consumer

Spell out unless the abbreviation is familiar to your audience.

BAML

Binary Application Markup Language

Basic

Beginners All-purpose Symbolic Instruction Code

Note capitalization. Don’t spell out.

BI

business intelligence

Spell out unless the abbreviation is familiar to your audience.

bi-di

bidirectional

Always spell out.

BIFF

Binary Interchange File Format

BIOS

basic input/output system

Don’t spell out unless the abbreviation is unfamiliar to your audience.

BISYNC

Binary Synchronous Communications

Do not use BSC.

BSC

Binary Synchronous Communications

Don’t use. Use BISYNC instead.

CBT

computer-based training

Don’t use. Use tutorial instead. For additional guidance, see CBT (Appendix A).

CD

compact disc

Don’t spell out. For CD types and additional guidance, see CD (Appendix A).

CDF

Channel Definition Format

When referring to the specification, use italic formatting and provide a version number.

CDS

Circuit Data Services

CE

collector’s edition

Always spell out. Note singular possessive. Always use title capitalization when this term is part of a product name.

CGA

color/graphics adapter

CGI

Don’t spell out unless the reference is unclear.

CIS

computer information systems

CISC

complex instruction set computer

Don’t spell out unless the abbreviation is unfamiliar to your audience.

CLR

common language runtime

CLS

common language specification

CMC

CMS

continuous media server

Don’t use. Use MMS instead.

CMY

cyan-magenta-yellow

Don’t spell out unless the abbreviation is unfamiliar to your audience.

CMYK

cyan-magenta-yellow-black

Don’t spell out unless the abbreviation is unfamiliar to your audience.

COFF

Common Object File Format

For the expanded form, use title capitalization to refer to the specification, but use lowercase to refer to the file format.

COM

COM+

As Component Object Model, don’t spell out.

As the name of a communications port (also known as serial port), use all uppercase followed by a number, as in COM1.

Be sure that the user cannot be confused about what COM means in your content.

As an extension and the indicator of a commercial organization in a URL, use all lowercase preceded with a period, as in .com file and Microsoft.com.

CPI-C

Common Programming Interface for Communications

CR/LF

carriage return/line feed

CSS

cascading style sheets

Spell out unless the abbreviation is familiar to your audience.

CTI

Computer-Telephony Integration

CTS

common type system

CUT

Do not use as an abbreviation for Coordinated Universal Time. Use UTC instead.

DAO

Data Access Object

DBCS

double-byte character set

DBMS

database management system

DCE

distributed computing environment

DCOM

distributed COM

Don’t spell out. Use this term only to refer to the DCOM wire protocol.

DDBMS

distributed database management system

DDE

Dynamic Data Exchange

DDI

Device Driver Interface

DDL

data definition language

DDNS

dynamic DNS

Don’t use either the abbreviation or the expanded form. Instead, refer to a DNS server that supports the dynamic update protocol. For additional guidance, see DNS (Appendix A).

DES

Data Encryption Standard

DFS

Distributed File System

DHCP

Dynamic Host Configuration Protocol

DHTML

dynamic Hypertext Markup Language

Use dynamic HTML (DHTML) on first mention.

DIB

device-independent bitmap

DIF

Data Interchange Format

DLC

Spell out when referring to downloadable content.

DLL

dynamic-link library

Do not use dynalink. Use lowercase (.dll) when referring to the file name extension.

DMOD

dynamic access module

DNS

Domain Name System

Not Domain Name Server. When referring to the DNS networking protocol, spell out on first mention. When referring to the Windows feature that implements the protocol, don’t spell out. For additional guidance, see DNS (Appendix A).

Don’t use this abbreviation to refer to the digital nervous system.

DoS

denial of service

Spell out unless the abbreviation is familiar to your audience. Hyphenate the spelled-out term when using it as an adjective, as in denial-of-service attack.

DOS

disk operating system

Don’t spell out. Avoid except as MS-DOS. See MS-DOS (Appendix A).

DSP

digital signal processor

DSS

DVD

digital versatile disc

Don’t spell out. For DVD types and additional guidance, see DVD (Appendix A).

EA

extended attributes

Always spell out.

ECC

electronic credit card

EFI

Extensible Firmware Interface

EGA

enhanced graphics adapter

EISA

Extended Industry Standard Architecture

EPS

encapsulated PostScript

EULA

End-User License Agreement

Don’t use. Use Microsoft Software License Terms instead. See Microsoft software license terms and license terms.

FAQ

frequently asked questions

Precede with the indefinite article a, not an. Spell out unless the abbreviation is familiar to your audience.

FAT

file allocation table

Always spell out when referring to the table. Don’t spell out when referring to the file system; always use FAT file system.

fax

facsimile

Don’t spell out. Don’t capitalize as FAX. All right to use as an adjective, as in “fax machine” and “fax transmission;” as a noun, as in “your fax arrived;” or as a verb, as in “fax a copy of the order.”

FB, fb

Facebook

Always spell out.

foo, foobar, fubar

Do not use. The word is slang derived from an obscene phrase meaning “fouled up beyond all recognition.” Use another placeholder or variable name instead. For example, use Example.exe or MyFile.doc.

FTP

File Transfer Protocol

Lowercase when used in an Internet address. Don’t use as a verb.

FTS

GAC

global assembly cache

Always spell out.

GDI

Graphics Device Interface

GIF

Graphics Interchange Format

GPI

graphics programming interface

GUI

graphical user interface

Don’t spell out unless the abbreviation is unfamiliar to your audience.

GUID

globally unique identifier

Don’t spell out unless the abbreviation is unfamiliar to your audience.

HAL

hardware abstraction layer

HBA

host bus adapter

HD

high-definition

Don’t spell out unless the abbreviation is unfamiliar to your audience.

HDTV

high-definition TV

Don’t spell out.

HDLC

High-Level Data Link Control

HMA

high-memory area

HPFS

high-performance file system

HTML

Hypertext Markup Language

Don’t spell out.

HTTP

Hypertext Transfer Protocol

Don’t spell out unless you are discussing protocols or URLs, or unless the abbreviation is unfamiliar to your audience. The abbreviation is lowercase when used in an Internet address. For additional guidance, see HTTP (Appendix A).

IaaS

infrastructure as a service

Don’t capitalize as IAAS. For additional guidance, see infrastructure as a service (IaaS ) (Appendix A).

IANA

Internet Assigned Numbers Authority

ICP

ICS

Internet Connection Sharing

Always spell out.

IDE

integrated device electronics, integrated development environment

Sometimes seen as integrated drive electronics. Spell out on first mention, using one term consistently.

IEEE

Institute of Electrical and Electronics Engineers, Inc.

IFS

installable file system

IHV

independent hardware vendor

IM

instant message, instant messaging

For additional guidance, see instant message.

I/O

input/output

Don’t spell out unless the abbreviation is unfamiliar to your audience.

IOCTL

I/O control

Spell out on first mention. On subsequent mention, all right to abbreviate as I/O control or IOCTL. Use only in content for a technical audience.

IP

Internet Protocol

Don’t spell out.

IPC

interprocess communication

IPX/SPX

Internetwork Packet Exchange/Sequenced Packet Exchange

IS

Information Services

ISA

Industry Standard Architecture

Don’t spell out unless the abbreviation is unfamiliar to your audience.

ISAM

indexed sequential access method

ISAPI

Internet Server Application Programming Interface

If API has already been spelled out, use Internet Server API (ISAPI) on first mention.

ISV

independent software vendor

ITV

interactive TV

JPEG

Joint Photographic Experts Group

Refers to both the standard for storing compressed images and a graphic stored in that format. Don’t spell out.

LADDR

layered-architecture device driver

LAN

local area network

Don’t spell out unless the abbreviation is unfamiliar to your audience.

LCE

limited collector’s edition

Always spell out. Note singular possessive. Always use title capitalization when part of a product name.

LCID

locale identifier, locale ID

Don’t abbreviate as LCID. Use LCID only as a data type.

LDAP

Lightweight Directory Access Protocol

LDTR

local descriptor table register

LINQ

Language-Integrated Query

LU

logical unit

MAC

media access control

Always spell out on first mention.

MAN

metropolitan area network

MAPI

Messaging Application Programming Interface

If API has already been spelled out, use Messaging API (MAPI) on first mention.

MASM

Macro Assembler

MCA

Micro Channel Architecture

MCGA

multicolor graphics array

MCI

Media Control Interface

MDA

monochrome display adapter

MDI

multiple-document interface

MFC

Microsoft Foundation Classes

MIDI

Musical Instrument Digital Interface

Don’t spell out unless the abbreviation is unfamiliar to your audience.

MIDL

Microsoft Interface Definition Language

MIF

Management Information Format

MIS

management information systems

Use IS instead, unless you must specifically refer to MIS.

MMS

Microsoft Media Server

Don’t precede with a definite article. Don’t use CMS.

MMU

memory management unit

MOF

Managed Object Format

MPEG

Moving Picture Experts Group

Don’t spell out. For additional guidance, see MPEG (Appendix A).

MS, MSFT

Microsoft

Always spell out, even in informal communications such as blogs or microblogs. MSFT is all right to use if you are referring to the stock ticker symbol.

MSMQ

Microsoft Message Queuing

Don’t use. Use Message Queuing instead. On first mention, you can use Message Queuing (also known as MSMQ).

MSN

The Microsoft Network

MSO

multiple service operator

MTA

message transfer agent

NA, N/A

not applicable, not available

Always spell out, even in tables. For additional guidance, see Tables (Appendix A).

NAICS

North American Industry Classification System

Pronounced “nakes.” Replaces Standard Industrial Classification (SIC).

NaN

not a number

Note capitalization.

NCB

network control block

NCSA

National Center for Supercomputing Applications

NDIS

network driver interface specification

NDK

network development kit

NetBEUI

NetBIOS Enhanced User Interface

Don’t spell out.

NetBIOS

network basic input/output system

Don’t spell out.

NFS

network file system

NIC

network interface card

NLS

national language support

NMI

nonmaskable interrupt

NOS

network operating system

NTFS

NTFS file system

The redundant phrase is correct. Don’t use NT file system or New Technology file system.

NTSC

National Television System Committee

ODBC

Open Database Connectivity

ODL

Object Description Language

ODS

Open Data Services

OEM

original equipment manufacturer

Don’t spell out unless the abbreviation is unfamiliar to your audience.

OLAP

online analytical processing

OLE

Object Linking and Embedding

Don’t spell out.

OOFS

object-oriented file system

OOM

out of memory

Always spell out.

OOP

object-oriented programming

OS

Don’t use as an abbreviation for operating system.

OSI

Open Systems Interconnection

PaaS

platform as a service

Spell out on first mention. Don’t capitalize as PAAS. For additional guidance, see platform as a service (PaaS) (Appendix A).

PANS

pretty amazing new stuff, pretty amazing new services

Refers to telephone services. See also POTS.

PARC

Palo Alto Research Center

PC

personal computer

Don’t spell out. All right to use in content that is informal in tone, in UI text where space is limited, or when referring to a feature or website that includes the term PC. In procedures, use computer. For additional guidance, see PC, PC-compatible.

PCMCIA

Personal Computer Memory Card International Association

Use PC Card instead of PCMCIA or PCMCIA card, to refer to the add-in memory and communications cards for portable computers.

PDF

Don’t spell out when referring to the file format.

PDLC

premium downloadable content

Not paid downloadable content. Spell out.

PE

portable executable

When using the abbreviation, always follow with file, as in PE file or PE file format.

PERT

program evaluation and review technique

PFF

Printer File Format

PIF

program information file

PII

personally identifiable information

Always spell out.

PIN

personal identification number

Don’t spell out unless the abbreviation is unfamiliar to your audience.

PnP

Plug and Play

Note capitalization. For additional guidance, see Plug and Play.

POTS

plain old telephone service

See also PANS.

PPP

Point-to-Point Protocol

PPPoE

Point-to-Point Protocol over Ethernet

PROM

programmable read-only memory

PSU

power supply unit

Always spell out.

PW

password

Always spell out.

QA

quality assurance

QBE

query by example

QFE

quick fix engineering

Don’t use. For additional guidance, see Out-of-band release terminology (Chapter 6).

RAID

redundant array of independent disks

RAM

random access memory

For additional guidance about referring to memory, see memory (Appendix A).

RAS

Remote Access Service is Windows-based software. The server is a host on a LAN equipped with modems.

RDBMS

relational database management system

RFID

radio frequency identification

RFT

revisable form text

RGB

red-green-blue

Don’t spell out unless the abbreviation is unfamiliar to your audience.

RIFF

Resource Interchange File Format

RIP

Always spell out on first mention to avoid confusion.

RIPL

remote initial program load

RISC

reduced instruction set computer

ROM

read-only memory

For additional guidance about referring to memory, see memory (Appendix A).

ROM BIOS

read-only memory basic input/output system

Don’t spell out.

RPC

remote procedure call

RTF

Rich Text Format

S+S

software-plus-services

Always spell out, but you can replace plus with a plus sign if space is limited. For additional guidance, see software-plus-services (Appendix A).

SAA

Systems Application Architecture

SaaS

software as a service

Don’t capitalize as SAAS. For additional guidance, see software as a service (SaaS) (Appendix A).

SAMI

Synchronized Accessible Media Interchange

SAP

Service Advertising Protocol

SAPI

Speech Application Programming Interface

If API has already been spelled out, use Speech API (SAPI) on first mention.

SBCS

single-byte character set

SCSI

small computer system interface

Pronounced “scuzzy.” The acronym takes the indefinite article a, not an.

SDK

software development kit

SDLC

SGML

Standard Generalized Markup Language

Don’t spell out.

SIC

Standard Industrial Classification

Replaced by North American Industry Classification System (NAICS).

SID

security identifier

SIM

subscriber identity module

Don’t spell out.

SIMM

single inline memory module

Don’t spell out unless the abbreviation is unfamiliar to your audience.

SLIP

Serial Line Internet Protocol

SMB

server message block

SMP

symmetric multiprocessing

SMTP

Simple Mail Transfer Protocol

SNA

Systems Network Architecture

SNMP

Simple Network Management Protocol

SOA

service-oriented architecture

For additional guidance, see service-oriented architecture (Appendix A).

SOAP

Simple Object Access Protocol

Don’t spell out unless the abbreviation is unfamiliar to your audience.

SPI

service provider interface

SQL

Structured Query Language

When referring to the language, SQL is pronounced “es-cue-el” and takes the indefinite article an, not a. When referring to Microsoft SQL Server, follow the guidance in SQL Server (Appendix A).

SSD

solid-state drive

For additional guidance about referring to drives, see drive (Appendix A).

STB

set-top box

Always spell out.

SVC

switched virtual circuit

SVGA

Super Video Graphics Array, Super VGA

Don’t spell out. For additional guidance, see Super VGA, SVGA (Appendix A).

SXGA

Super Extended Graphics Array, Super XGA

Don’t spell out.

TAPI

Telephony Application Programming Interface

If API has already been spelled out, use Telephony API (TAPI) on first mention.

TBD

to be determined

Always spell out.

TCP/IP

Transmission Control Protocol/Internet Protocol

Don’t spell out.

TIFF

Tagged Image File Format

Don’t spell out.

TIP

Transaction Internet Protocol

TP

transaction processing

Always spell out.

TSPI

Telephony Service Provider Interface

TSR

terminate-and-stay-resident

TTY

teletypewriter

TV

television

All right to use without spelling out.

UDP

User Datagram Protocol

UEFI

Unified Extensible Firmware Interface

If EFI has already been spelled out, introduce as Unified EFI (UEFI).

UI

user interface

Don’t spell out unless the abbreviation is unfamiliar to your audience.

UMB

upper memory block

UML

Unified Modeling Language

UNC

Universal Naming Convention

Spell out on first mention unless you are positive that your audience is familiar with the abbreviation.

UPC

universal product code

UPnP

Universal Plug and Play

Don’t spell out. This abbreviation is trademarked. For additional guidance, see UPnP (Appendix A).

UPS

uninterruptible power supply

Spell out unless the abbreviation is familiar to your audience.

URL

Uniform Resource Locator

Don’t spell out unless the abbreviation is unfamiliar to your audience. You can use address instead of URL. The acronym takes the indefinite article a, not an. For additional guidance, see URLs, addresses (Chapter 7).

USB

universal serial bus

Don’t spell out. Don’t use as a noun, only as an adjective, as in USB storage device.

UTC

Coordinated Universal Time

This is the internationally recognized name for Greenwich Mean Time. Don’t spell out as Universal Time Coordinate.

UTF-n

UCS Transformation Format –n-bit.

Don’t spell out.

UUID

universally unique identifier

UXGA

Ultra Extended Graphics Array, Ultra XGA

Don’t spell out.

VAR

value-added reseller

VB

Visual Basic

Spell out except when referring to VBA or VBScript.

VBA

Microsoft Visual Basic for Applications

VBScript

Microsoft Visual Basic Scripting Edition

VCPI

virtual control program interface

VCR

video cassette recorder

Don’t spell out.

VGA

Video Graphics Array, Video Graphics Adapter

Don’t spell out. For additional guidance, see VGA (Appendix A).

VIO

video input/output

VM

Always spell out to avoid confusion. When referring to Visual Studio 2010 VM Factory, spell out as Virtual Machine Factory on first mention. On subsequent mention, use VM Factory.

VRML

Virtual Reality Modeling Language

VSAM

virtual storage access method, virtual storage access memory

VTP

virtual tunneling protocol, or VLAN trunking protocol

W3C

World Wide Web Consortium

Write out as “World Wide Web Consortium” on first mention.

WAN

wide area network

WBEM

Web-based Enterprise Management

WEP

Wired Equivalent Privacy

Don’t spell out. Don’t use as a noun, only as an adjective, as in WEP encryption key.

Wi-Fi

Note capitalization and hyphenation. When possible, use a general phrase such as wireless network instead. For additional guidance, see Wi-Fi (Appendix A).

WML

Wireless Markup Language

WOSA

Windows Open Services Architecture

WSDL

Web Services Description Language

WWW

World Wide Web

Capitalize all words when using the expanded form. Otherwise, use the web. All lowercase (www) when used in an Internet address. For additional guidance, see World Wide Web and Web (Appendix A).

WYSIWYG

what you see is what you get

Don’t spell out unless the abbreviation is unfamiliar to your audience.

XAML

Extensible Application Markup Language

XGA

Extended Graphics Array

Don’t spell out.

XHTML

Extensible Hypertext Markup Language

Use Extensible HTML (XHTML) on first mention.

XML

Extensible Markup Language

Don’t spell out.

XMS

extended memory specification

XSL

Extensible Stylesheet Language

ZAW

Zero Administration for Windows

Spell out on first mention.