Networking Dynamics Corporation CompuFax, User Manual

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3.2.1 Tex t Files
The simplest file type is a regular text file, such as the ones we sent in the examples of the previous chapter.
These files are also referred to as printer format files or ASCII (American Standard Code for Information
Interchange) files. This type of file can be created with a simple text editor.
3.2.2 Bit m apped Files
In addition to text files, there are also graphics or bitmapped files. The difference between a text file and a
bitmapped file is that in a text file, the letter A, for example, is represented by a number, while in a bitmapped
file the same letter is represented as a pattern of black and white dots (bits) that are arranged in the shape of
the letter A.
The example below illustrates this:
TEXT (ASCII) GRAPHICS (BITMAPPED)
o ooooo
A = 65 o o o
E = 69 o o oooo
o o o o o
o o ooooo
The ASCII system is the more efficient method of transmitting data, but is limited to text only. To send
pictures, you need bitmapped files. All files, including text files, are actually sent from one fax modem to
another, as bitmapped files. When you send a text file, CompuFax first converts it into a bitmapped file
before sending it on to the receiving fax station. Since bitmapped files are much bigger than text files and
therefore take longer to transmit, various compression methods have been devised, to reduce the file size. The
compression method used by fax modems is called the T.4 standard format), or T4 for short.
3.2.3 Post Sc ript Files
Another type of file is a PostScript file, which is actually a text file that describes how a page is to be printed.
If you try to print a PostScript file to a printer that does not "understand" the PostScript language, you get a
lot of gobbledygook.
CompuFax has a built-in PostScript interpreter. 1 , which converts the PostScript file you may wish to send
into a T4 bitmapped image of how the final result is supposed to look on the page and then transmits it to the
receiving fax station, where it is processed like a regular fax document. To make it easy for CompuFax to tell
the difference between the three types of files, it assumes that all T4 file names have a .T4 file extension and
all PostScript files have a .PS extension. Any other extension is considered to refer to a text file, although
your System Manager may have changed these rules. 1 PostScript file conversion requires a PostScript license
option.
If you are sending files that do not follow the above rules, you can use the / FORMAT qualifier to specify the
correct file format. For example:
$ FAX SEN D FILE.COMPRESSED / FORMAT= T4 / N UM= 1-555-123-4567