- published: 11 Mar 2013
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A type code is the only mechanism used in pre-Mac OS X versions of the Macintosh operating system to denote a file's format, in a manner similar to file extensions in other operating systems. Codes are four-byte OSTypes. For example, the type code for a HyperCard stack is STAK; the type code of any application program is APPL.
Mac OS X retains type codes, but supports filename extensions as well. The deprecation of type codes (and creator codes) over the older extension system, popularised by PDP-11 systems (RT-11, RSX-11, etc.), CP/M, and most recently by Microsoft's MS-DOS, has been very controversial with Mac users. The type and creator system is considerably richer and more sophisticated than that provided by extensions, and many users felt that adopting DOS conventions is a backward step. They claim that type and creator information rightfully belongs to the metadata associated with a file, and is therefore illogically placed within the file's name, where its presence can cause problems for the user. Apple defends the decision by saying that extensions have become the de facto standard for indicating file type, and they need to work seamlessly with the rest of the industry.
Type may refer to:
In philosophy:
In mathematics:
In computing:
In sociology:
Other:
A code is a rule for converting a piece of information (for example, a letter, word, phrase, or gesture) into another form or representation (one sign into another sign), not necessarily of the same type.
In communications and information processing, encoding is the process by which information from a source is converted into symbols to be communicated. Decoding is the reverse process, converting these code symbols back into information understandable by a receiver.
One reason for coding is to enable communication in places where ordinary spoken or written language is difficult or impossible. For example, semaphore, where the configuration of flags held by a signaller or the arms of a semaphore tower encodes parts of the message, typically individual letters and numbers. Another person standing a great distance away can interpret the flags and reproduce the words sent.
In information theory and computer science, a code is usually considered as an algorithm which uniquely represents symbols from some source alphabet, by encoded strings, which may be in some other target alphabet. An extension of the code for representing sequences of symbols over the source alphabet is obtained by concatenating the encoded strings.