John Cletheroe's
PC And Internet Hints

PC And Internet Glossary - Including File Extensions - T

T & L

See Transformation And Lighting.

T1 Line

One type of very high capacity telephone line used for data transmission.

Tab Key

The tab key is above the Caps Lock on the lefthand side of the keyboard. It is marked with two horizontal arrows pointing in opposite directions.

In a Windows dialog box, use the Tab key to move the cursor to the next field. Use SHIFT/Tab to move to the previous field.

In a word processing program, don't use multiple tabs to position text. There is always a superior method of positioning text which is not only much simpler but will also make it easy to modify the text in the future.

Table

A term used with many modern database programs. Since many of these programs hold all of a system's data in one physical disk file, a different name is required for what was traditionally called a file - "table" is that name. Therefore a table consists of a homogenous and organised set of records and fields.
A rectangular grid of cells in a word processor, web browser, etc. The cells can each contain text which automatically word wraps within each cell. In addition, cells can have borders of various types, or no printed borders at all. As well as their obvious uses, such tables when given invisible borders can also be extremely useful in laying out pages, for example a table with one row, two columns and an invisible border can be used to solve the problem of having the recipient's and the sender's addresses at the top of a letter. Large tables can be used to lay out text in vertical columns. A three-column table with invisible borders is a very good solution to the problem of laying out meeting minutes, with the subject in the lefthand column, what was said in the centre column and a list of action points in the righthand column.
In HTML, tables with invisible borders are an excellent method of laying out a web page.

Tabs

In a word processing program tabs can be used to easily position text in vertical columns.

Default tabs (sometimes called preset) tabs are simple to use but you cannot adjust their position or their type. Because of these limitations they are best avoided.
User defined tabs can be inserted at any position across the width of the page. They allow text to be left aligned, right aligned, centred or decimal aligned at the tab position.

As well as tabs, tables and newspaper columns can be used to lay out text in vertical columns.

TAF

File extension. Adrift text adventure. I do not know whether TAF files can contain viruses or not; it seems unlikely.

Tag

A command in an HTML file, contained inside angle brackets, which controls the layout of the text, inserts a graphic, or creates a hypertext link, etc. For example the <HR> tag creates a horizontal rule (a horizontal line).

TAPI

Telephony Application Programming Interface. Associated with dial-up networking in Windows.

Target File(s)

The file or files created as a result of a program's installation procedure. Most programs' installation procedures offer a choice of directory for the target files, with a subdirectory of C:\PROGRAM FILES usually presented as the default. Most installation procedures also install some target files such as DLL's or device drivers in C:\WINDOWS or one of its subdirectories.

TAS

File extension. Adrift text adventure saved game. I do not know whether TAS files can contain viruses or not; it seems unlikely.

Task

A program loaded into memory and running. Some programs create several tasks, in which case the individual tasks are sometimes called threads.

TCA

Trusted Computing Alliance. See TCPA.

TCO

Total Cost Of Ownership. A concept often used by the manufacturers and sellers of expensive products, claiming that less expensive products are more expensive in the long run. In most cases, pure spin.

TCP/IP

Transmission Control Protocol/Internet Protocol. The way all information is transmitted on the Internet.

TCPA

Trusted Computing Platform Alliance. An initiative by Intel, Microsoft, Compaq, Hewlett Packard and IBM which is an attempt to make the PC more secure and more reliable. However, some people are concerned that TCPA may also include extremely restrictive digital rights management copyright protection systems which could be used by governments for censorship purposes and by companies for anti-competitive purposes. Palladium (recently renamed Next Generation Secure Computing Base) is the software that Microsoft plans to incorporate in future versions of Windows that will build on the TCPA hardware. Also called TCA (Trusted Computing Alliance).

TechNet

A little-known but highly valuable Microsoft product giving technical details of their products. TechNet consists of a set of CD's sent out each month and is only available by subscription. For a private individual the cost of a year's subscription is unrealistic but for a company it would be a worthwhile investment. It is a pity that you cannot purchase a single month's disks for a lower cost, since unless there is a major new product the information does not differ very much from issue to issue. The information on TechNet consists mainly of technical descriptions of new products together with Knowledge Base (see that entry). Most of the information on TechNet is also available on Microsoft's web site.

Telco

A telco is a telephone company. For example, BT and Mercury are telcos.

Telnet

A program which runs on your computer and which makes it emulate a VDU, enabling you to conduct a terminal session on a remote computer. Most Internet users nowadays will have no use for Telnet.

Tera

1,099,511,627,776 (1024 x 1024 x 1024 x 1024, 2 to the fortieth power).

TEXTURE

File extension. Used in Auran's Trainz 2004 Railway Simulator program, for (amazingly enough) textures. Textures are two-dimensional patterns which can be applied to the sides of three dimensional objects held as meshes, in order to create images of them.

TGA

File extension. An obscure graphics file format.

Theme

I think a "theme" is a collection of Windows appearance settings (the colours and sizes of the objects which appear in the vast majority of Windows programs). I suspect that you may need to install Microsoft Plus in order to make use of Themes.

THG

Tom's Hardware Guide http://www.tomshardware.com - a web site which offers a large amount of extremely useful information on the subject of computer hardware. External link verified Sep-03.

Thread

Virtually the same as a task (see that entry).

Three Finger Salute

A colloquial expression for CTRL/ALT/DEL, which used to reboot a computer but which now brings up the Task List.

THREED

Files with the prefix THREED, possibly a suffix, and various extensions (i.e. THREED*.*). 3D custom controls (ActiveX controls) for Visual BASIC. Often distributed with Visual BASIC programs and installed by their installation routines, sometimes in a sub-folder of C:\Windows, sometimes in the program's target folder. I suspect that only one copy of each version of each file is required, in C:\Windows\System. I think these controls were originally created by Microsoft but are now published by Sheridan Software Systems, Inc (or possibly vice-versa) and are therefore sometimes called the Sheridan controls.

Thumb Drive

A colloquial name for USB flash memory keys, which appears to Windows as a extra disk drive.

Thumbnail

A small copy of an image (a photograph, etc) displayed for preview purposes.

Thunderbird

The email program associated with the Firefox web browser. See Firefox.

Thunk

A small section of a program which converts parameters between 16 bits and 32 bits, thus allowing a 16-bit program to use a 32-bit subroutine or vice-versa.

TIF

File extension. Tagged Image File. A compressed bitmapped image file format.

Tilde

~ (see that entry).

TiVo

See PVR.

TLA

Three Letter Acronym. See also ETLA. :)

TLB

File extension. Visual BASIC V6 Remote Automation TypeLib (Type Library) file. See also Type Library. I do not know whether TLB files can contain viruses or not.

TLD

Top Level Domain (see that entry).

TLS

Transport Layer Security. A protocol for transmitting information over the Internet in an encrypted form, similar to SSL.

TMP

"Temp". File extension. Temporary file. TMP files are normally deleted by programs after they have been used but if a program is badly written, if a program crashes or if the computer locks up then this may not be done. Therefore it is well worth searching for all the TMP files on your computer and deleting them every so often. Shut down all programs before doing this in case they have any legitimate TMP files open.

TNEF

Transport Neutral Encapsulation Format. A format for formatted email messages, somewhat similar to Rich Text Format.

The list of contents of a document, such as appears at the front of a book. Many word processors can produce tables of contents automatically, complete with the page numbers.
CD's have TOC's. For some reason which I do not understand, it takes quite a long time for CD-R/CD-RW drives to write TOC's to disks. Perhaps numerous copies are created to guard against corruptions which would make the disk's contents inaccessible.

Tool

Microsoft KnowledgeBase article 824684 includes the following definition of this term as used by Microsoft: "A tool is a utility or a feature that helps to complete a task or a set of tasks."

Top Level Domain (TLD)

.ca, .com, .de, .edu, .gov, .net, .nl, .uk, etc. That part of a domain name which appears at the righthand end.

Tracking Cookie

A cookie that is shared among two or more web pages for the purpose of tracking a user's surfing history.

Transformation And Lighting

A term used in computer graphics, especially with regard to 3D. The meaning of "lighting" is obvious enough, although the subtleties and complexities of lighting effects in 3D are very considerable. "Transformation" presumably refers to the matrix transformation geometry calculations which are at the heart of 3D graphics. All modern video boards perform most T & L calculations themselves, offloading this highly intensive work from the main processor.

Tree

A data structure which resembles a real tree, which branches and leaves. Good examples include the directory (folder) tree displayed by Windows Explorer, or the folder tree displayed in many email programs. Programmers seem rather hazy about the fundamental biology of plants, using the terms branches, leaves and roots together freely.

Trilinear Filtering

A term used in computer graphics. Trilinear filtering is the deliberate blurring of adjacent pixels, so as make them appear to merge together. Bilinear filtering seems to be a slightly more advanced variant on the bilinear filtering concept.

TRK

File extension. See this entry on my Trainz Wordz page.

Trojan Horse

A program which maliciously performs a different action to that which its name and accompanying documentation implies. For example, a program which is advertised as being a harmless utility or game might actually delete or corrupt a large number of files, or re-format the user's hard disk. It is of course also possible that a program could perform both its advertised harmless function and a secret malicious operation. Strictly speaking, Trojan horses are not viruses, because they are not self-replicating. The name comes from the wooden horse of Troy in Greek legends.

TRS-80

An early home computer sold by the computer known as Tandy in Europe and Radio Shack in the USA and Canada, hence the initials.

TRS2004

Trainz Railway Simulator 2004, a program published by Auran.

True Color

24-bit or 32-bit colour. 24-bit colour provides 16,777,216 colours. 32-bit colour also provides 16,777,216 colours but with the additional facility to include transparency information (for fog effects, etc).

TrueType Font

A type of font which will be displayed and printed as accurately as possible in all font sizes with Windows. Always use TrueType fonts wherever possible.

TSO

File extension. See this entry on my Trainz Wordz page.

TSR

Terminate and Stay Resident. A type of program from the days of MS-DOS, which sat in the background waiting to pop up and be used when a certain condition occurred, for example when the user pressed an unusual combination of keys. Small utility programs (applets in today's terminology), obscure device drivers and network drivers were examples of TSR's. The programs in the System Tray are the Windows equivalent of TSR's, although I suspect that it is also possible to create a program which runs under Windows with no visible evidence on the screen whatsoever.

TTF

File extension. TrueType Font file.

TWAIN

A data transfer protocol associated with scanners (and possibly some types of digital cameras which are permanently connected to PC's).

TXT

File extension. Text file, or ASCII text file. Such files contain no formatting other than carriage returns and can be opened with Notepad.

Type Library

A term used in object oriented programming. Type libraries can either be files in their own right or included as part of some other types of files (including DLL, EXE and OLB files). I think type libraries store information about objects but how they differ from OCX files I do not know. Type libraries seem to be very similar in concept to Java class files. See also OLB and TLB.

Typing Replaces Selection

A feature of Windows' design which confuses many users, although to be fair it is very difficult to suggest a better solution.

A section of text can be selected either by the user dragging over it with the mouse or (in a dialog box only) by the user pressing the TAB key to move into the field.

When selected, the section of text is highlighted by being displayed in reverse video.

If the user then presses a normal key on the keyboard the entire selected section of text is deleted and replaced by the single character which was typed (and successive characters added as the user types them). If you press a key by mistake and immediately realise what you have done, in most programs you can use EDIT > UNDO to cancel the effect.

It is possible to retain the original text and edit it, which is often extremely useful. To do this, press the cursor left or cursor right key, or click with the mouse in the selected text. The selection will be cancelled and the text can then be edited as normal.

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Most recently modified 18-Feb-08