Data Types in A Resource Fork
The smallest elements making up a resource fork are called data types. There are several data types. After a resource fork is accessed, its contents can be found by reading it in as appropriate for the data types defined in advance. Placing definitions inside the program stating how data is to be treated makes it possible to store resources called TMPL resources as well. Using this method increases the visibility of the data when viewed with a program such as ResEdit, making later editing simpler. As the Macintosh platform originated with Motorola-based processors (68k and PPC), the data is serialized to disk in big endian format.
The following is a list of the major data types, in alphabetical order.
| Data type (actual name) | Description |
|---|---|
| BBIT (binary bit) | Represents a single boolean bit (true or false). Normally the number of BBITs must be a multiple of 8. |
| BOOL (boolean) | Represents a boolean value. It consists of 2 bytes; 256 is true, and 0 is false. |
| CHAR (character) | Represents a one-byte character. |
| CSTR (C string) | Represents a string of the form used in the C programming language: a null-terminated string of bytes. |
| DLNG (decimal long word integer) | A decimal long word (4 byte) integer. Represents values between approximately −2.1 billion and 2.1 billion. |
| HEXD (hex dump) | Indicates that the data from this position to the end is hexadecimal. This is used to represent code resources or compressed data. |
| HLNG (long word hexadecimal) | This data is treated as a 4 byte hexadecimal value. It is used, among other things, to represent integers greater than 2.1 billion, such as unsigned long values in C. |
| PSTR (Pascal string) | Represents a Pascal string, with the first byte giving the length of the string. |
| TNAM (type name) | A string representing a value such as a creator code, which is always 4 bytes long. |
| RECT (rectangle) | Represents the coordinates of the corners of a rectangle. Always 8 bytes long. |
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