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I know that in computers there are 4 types of characters:

  1. Regular characters (numbers or typical language letters).
  2. Control characters (characters used to effect how a documented is analyzed by a robot or a program) like Line FInish (LF) or Carriage Return (CR).
  3. Meta characters (any given character represting something other than itself).

Can we say that the BOM characters is also a control character like LF or CR?

  • You say "there are 4 types of characters" and then list only 3 ... – DavidPostill Apr 26 '17 at 20:00
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Can we say that the BOM characters is also a control character like LF or CR?

No. It is more like a signature:

Q: What is a BOM?

A: A byte order mark (BOM) consists of the character code U+FEFF at the beginning of a data stream, where it can be used as a signature defining the byte order and encoding form, primarily of unmarked plaintext files. Under some higher level protocols, use of a BOM may be mandatory (or prohibited) in the Unicode data stream defined in that protocol.

Source FAQ - UTF-8, UTF-16, UTF-32 & BOM


In your question you state:

Control characters (characters used to effect how a documented is analyzed by a robot or a program) like Line FInish (LF) or Carriage Return (CR).

This above is incorrect.

  1. LF stands for Line Feed not Line Finish.

  2. Control Characters don't have anything to do with how a document is analysed:

A control character or non-printing character is a code point (a number) in a character set, that does not represent a written symbol. They are used as in-band signaling to cause effects other than the addition of a symbol to the text.

Source Control character

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By BOM, I assume you mean the Unicode Byte Order Mark code point.

You are inventing your own definitions, so define BOM to be any type you want.

The designers of the Unicode Standard have their own definitions. See The Unicode Standard, version 9.0.0, section 3.4 Characters and Encoding. Definition D10a defines "Code point type" as "seven fundamental classes of code points in the standard: Graphic, Format, Control, Private-Use, Surrogate, Noncharacter, Reserved". Those types are explained at length in Chapter 23 Special Areas and Format Characters. Section 23.8 Specials defines U+FEFF, the "byte order mark", as having Code Point Type of "Special".

So, the designers of the Unicode Standard have a list of 7 code point types, and the Byte Order Mark is of type "Special". Incorporate that into your own definition however you wish.

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