The tab key on the computer represents the tab key or table creation. Its function is to advance the cursor to the next anchor point. In other graphics applications, the tab key moves input focus to the next control.
#The operating environment of this article: windows10 system, thinkpad t480 computer.
On a computer keyboard, the Tab key (short for tabulator key or tabular key) is used to advance the cursor to the next anchor point.
Purpose of the tab key:
In word processing programs, the Tab key is usually used to advance the cursor to the next anchor point. In other graphical applications (GUI), the Tab key moves input focus to the next control.
Positioning characters:
ASCII contains many positioning control characters used to align text. The most well-known and common positioning character is horizontal positioning (HT). The numeric code in ASCII is decimal 9, which can also be represented by Ctrl I or ^I. Vertical positioning (VT) also exists in ASCII and is represented by the numeric code 11 (Ctrl K or ^K). The code for horizontal positioning in EBCDIC is 5, while the vertical positioning is 11 as in ASCII. Usually the Tab key on a standard keyboard produces horizontal positioning characters. The horizontal positioning character in Unicode is :
. Initially, printers used mechanical positioning points to indicate the direction of the Tab: horizontal positioning used a row of movable metal forks, and vertical positioning used a ring the same width as the page. Perforated polyester film. These mechanical points are initially set manually to match the preprinted format loaded into the printer. Later, it was oriented to pre-programmed printers, using control characters to set and clear positioning characters: ISO 6429 includes handles 136 (set table positioning horizontally), 137 (set table positioning horizontally), and 138 (set table positioning vertically) .
In practice, settable anchor points were quickly replaced by fixed anchor points, with the unwritten unit of 8 characters horizontally and 6 vertical lines (usually 1 inch). The printing program can easily submit the necessary whitespace or newline characters to move to any position on the form, and this positioning method is far more reliable than a non-standard method with a specific mode. Anchor characters then became a way of data compression.
Although 5 characters was half an inch, and paragraph indentation was very common at that time, due to the limitations of digital electronic products at the time, it eventually evolved to 8 characters as the positioning unit, because calculations in binary were more complicated easy.
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