John Cletheroe's
PC And Internet Hints

PC And Internet Glossary - Including File Extensions - L

L1 Cache, L2 Cache

See "Cache".

LAN

  1. "Lan". Local Area Network. A network belonging to an organisation at one site with no telephone line connections (only network wiring) between its parts. However, one LAN might well be connected to one or more other LAN's at other sites via phone lines, in which case the phone line connections between the LAN's (or the entire system of LAN's and phone line connections) is called a WAN - wide area network.

  2. File extension. Language file. A file containing language specific text, for example a program's menu options and error messages in English, French or German, etc. I do not know whether LAN files can contain viruses or not; it seems unlikely.

LAPM

Link Access Procedure - Modems. A link-level error-correction protocol for dial-up modems, standardised as V.42.

Late Binding

See Early Binding.

LBA

Logical Block Addressing. A system, part of the BIOS or the hard disk controller, which enables some versions of MS-DOS and Windows to circumvent the restriction on accessing IDE hard disks with more than 504 megabytes (1024 cylinders). Microsoft KnowledgeBase article 122052 offers more information on the subject.

LDAP

Lightweight Directory Access Protocol.

LDB

File extension. A record locking information file associated with a Microsoft Access database. I do not know whether LDB files can contain viruses or not; it seems unlikely.

LE

In the suffix after the model number of a video board, this means that the board is a special cut-down version supplied to computer manufacturers for fitting in their products. The power of the SE version of a video board may be only half that of the normal board. The full range of suffixes is SE (much less powerful than standard), LE (much less powerful than standard), no suffix (standard), Pro (more powerful than standard), XT (much more powerful than standard) and XT PE (very much more powerful than standard).

Leased Line

A permanent telephone line connection between two computers. Same as private circuit. The connection may be via a conventional voice line or via one of several types of more expensive higher quality lines. Leased line/private circuit is the opposite of dial-up.

Left Click

To click the left mouse button.

Left Delete Key

The key with a large left pointing arrow, located above the RETURN key. Pressing the left delete key deletes the character to the left of the cursor and closes the gap that would otherwise be created. If a section of text or one or more objects are selected, pressing either right delete key or the left delete key will delete whatever is selected. See also Right Delete.

Legacy

Old, but still in use. The term can apply to hardware or software. There is an implication of incompatibility with a modern version of the same item. There is also an implication that the legacy item must be retained because the cost or effort of converting to a modern equivalent would be excessive or would take a long time.

Less than

< (see that entry).

Level 1 Cache, Level 2 Cache

See "Cache".

LGC, LGD, LGE, etc

File extensions. These files are created automatically by Windows 98 as part of its habit of automatically moving program files to other places on a hard disk in an attempt to make them load more quickly. LGC files refer to C:, LGD to D:, LGE to E: and so on. Each file is stored in the same folder as the program it refers to (or perhaps in C:\WINDOWS\APPLOG ?) and has the same filename as the program. LGC (etc) files are relatively small ASCII text files. The contents consist of numerous lines of hexadecimal numbers and filespecs, vaguely similar to registry entries. I do not know how safe it is to delete these files. I do not know whether these files can contain viruses or not; it seems unlikely.

See also Defrag, Defragmentation.

Opinion: In my experience the physical position of files on a hard disk has no perceptible effect on loading time. By the way, nor does defragmenting. The thought of a modern Microsoft program attempting to do something as complicated as moving program files automatically fills me with dread.

LHSP

A folder in Windows ME, probably associated with a text-to-speech facility. I do not know what the letters stand for, if anything.

LIBRA

Low-Cost Integrated Broadband Radio Access. An Internet access system involving radio transmitters and receivers mounted on tethered balloons, located at an altitude of 1,500 metres. A company called SkyLinc is promoting such a system for rural areas of Britain. At a wholesale price of £300 a month the cost would appear to match the technology - sky high.

Library

A set of subroutines, functions and/or classes (depending on the programming language), developed as additions to the core language, and intended for use by all developers within an organisation.

Libraries are often claimed to have advantages such as imposing standards, making development easier for beginners, and the holy grail of reusable code.

Opinion: In practice, libraries rarely fulfil any of these promises. They are often developed by programmers who have little contact with users or the real world. Libraries often include technically clever tricks which don't quite work in practice, leading to frequent runtime problems. As libraries are expanded to cope with an increasing number of real-world situations, they become extremely complex and difficult to maintain. The extra complexity of compilation with a library can be significant. The extra processing involved in handling library calls at runtime can sometimes be significant. The concentration of power into the hands of the library writers is not usually healthy or indeed wise, should a key person leave the organisation. Documentation of libraries is often very poor or non-existent, making life very significantly more difficult for beginners. For all these reasons, the use of libraries is to be treated with great caution. I feel it is generally better for a group of programmers to exchange ideas and techniques and in most cases stick to using the core language.

LIFO

Last In First Out. A programming technique which is extremely useful for holding the control information related to nested subroutines, nested loops, etc. See also FIFO and stack.

Line In

A socket on a computer or a sound card, to which any analog sound source such as an amplifier or audio mixer can be connected. Given appropriate software the incoming sound can be played by the computer or recorded as a sound file.

Link

  1. A stage in the program compilation process. I've always thought of linking as the integration of calls to external subroutines (operating system calls, library subroutines, etc). However, an alternative definition describes it as the process of assigning a value to a symbolic placeholder. During compilation the compiler assigns symbolic addresses to some variables and instructions. When the program is linked, the program replaces the symbolic addresses with real machine addresses. Linking is sometimes called binding (although there may be a slight technical difference).

  2. A hypertext link from one web page to another.

Linked List

A programming technique. Information is ordered in sequence by means of links from each item to the next. By modifying the links when items are added and removed the sequence can be preserved without physically moving the bulk of the data.

Linux

An operating system, generally considered to be far smaller, faster, more reliable, less demanding of hardware and less expensive than Microsoft Windows. Linux is mainly used on servers, although it can also be used on networked end-user PC's and standalone PC's. It is even possible to obtain versions of Linux which can be installed in the same hard disk partition as MS-DOS and Windows (DragonLinux is one example). I believe it is also possible to make a PC boot to MS-DOS/Windows or true Linux as desired. Most modern versions of Linux include a GUI (graphical user interface).

Some sources say that Linux is difficult to install and configure, other sources say this is no longer the case with modern versions. There are several versions of Linux, of which Red Hat is one of the best known. UK computer shops such as PC World and Software Warehouse are now selling some of these packages. Programs designed for DOS, Windows or Apple Macintosh computers will not run under Linux. Star Office is a well known word processing/spreadsheet suite for Linux which seems to generally receive very good reviews. Linux versions of a few games are now beginning to become available in shops in the UK. I do not know if Internet software is supplied inherently with Linux; if not then presumably it is widely available.

Although it is currently receiving a great deal of attention in the IT press I have yet to have a visitor to my web site recorded as being a Linux user (although that may be due to a bug with the system which records the operating systems of such visitors).

The syntax and commands of the Linux command line language are considerably more obscure and difficult to learn than those of MS-DOS. I have not seen a Linux GUI and so cannot comment on how they compare with Windows.

Question: "lin - ux", "line - ux",...? Does anyone know how "Linux" should be pronounced?

LINX

"Lynx". London Internet Exchange. The hub for Internet backbone connections in Britain.

ListServ

An email mailing list handling program. Subscribers to a mailing list send commands to the ListServ program in the form of email messages. There are several other similar programs including MajorDomo.

LM:

Microsoft KnowledgeBase article title prefix for articles relating to Microsoft Liquid Motion, which appears to be somewhat similar to MacroMedia Shockwave.

LMZ

Local Machine Zone. Files stored on a computer's hard disk and its own floppy disk drive, CD drives, etc. One of the security zones in Internet Explorer. Unfortunately, Internet Explorer's security configuration does not allow the local machine zone settings to be changed. Even worse, items in the local machine zone are given full permission to perform whatever operations they wish. Not a very clever idea, I think, as many users save web pages on their hard disk for later reading while offline.

LNK

Link. Shortcut file. For DOS programs, a PIF (program information file). LNK files can contain instructions which could perform undesirable operations on a computer.

LOADQM.EXE

A program: Query Manager.

LOADWC.EXE

A program: Windows Update Checker.

Local Loop

The phone line between the exchange and your house. In the UK the local loop is currently operated exclusively by BT but it is due to be opened up to other telephone companies before long, which should (it is hoped) see a drastic reduction in prices and increase in available services such as ADSL.

LOG

File extension. Log file. A record of the operation of a program, which often gives technical information which can be very helpful for checking the program or diagnosing problems. Most but not all log files are ASCII text files. Some log files record the operation of installation programs and are therefore "once only". Some log files record the normal everyday operation of programs and therefore grow in size which can be a problem. Sometimes programs limit the size of their log files, sometimes you have to regularly manually delete old log file entries or the entire log file, sometimes via an option in the program, sometimes using an editor such as Notepad. Sometimes a log file is not written unless an appropriate option is enabled (the Windows modem log file being a good example). I do not know whether LOG files can contain viruses or not; it seems unlikely but it may depend on the particular program.

LOGO

A computer programming language which simulates the movement of a "turtle", designed to teach children programming and geometry. The language has commands such as "FORWARD 10" and "LEFT 45" (meaning turn left 45 degrees).

Longhorn

Microsoft's code name for the next version of Windows, the successor to Windows XP, which is currently being developed. Longhorn's major new feature was intended to be a new filing system called WinFS (see that entry). Microsoft's decision in August 2004 to abandon WinFS reduces Longhorn to little more than another bug-fix release of Windows.

Lossy

A lossy file format or transmission protocol means that some data is lost but in a controlled fashion so as to undetectable. Examples of lossy formats include JPG for photographs and MP3 for sound.

Lower case

Small letters.

LSASS

Local Security Authority Subsystem Service, or Local Security Authentication Server. A component of Windows XP that verifies the validity of user logons.

LSP

Layered Service Provider. An internal system in Windows XP.

Lurker

Someone who accesses material on the Internet but fails to make any contributions themselves. In the Internet's early days lurkers were frowned upon; nowadays most Internet users are lurkers. It is very wise to lurk for some time before posting messages to a news group, to get an idea of its subject-matter, style and etiquette. It is generally thought that J Michael Straczynski got the name of lurker for the inhabitants of the Downbelow section of Babylon 5 from the use of the word on the Internet.

LView

An excellent shareware program for manipulating image files. It allows conversion between a wide range of formats, cropping (removing part of an image), re-sizing, adjustment of brightness, contrast and colour balance, and various other features. LView cannot create images - it is not a drawing program.

Lycos

A well known search engine.

http://www.lycos.com

LZW

Lempel-Ziv-Welch. One form of run-length encoding, named after its inventors.
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