Every Macintosh application is a collection of discrete modules of data called
resources. When a programmer assembles or compiles his source code into object
code, the code is placed in a resource of type CODE. The programmer may then
link to his CODE resource other data resources his code will use. These may
include resources such as menus, fonts, windows, controls, dialog boxes, icons
or pictures.
At power up, the Resource Manager initializes in ROM. To refer to and access
resources, which are grouped logically by "type", application code can use
the Resource Manager on an "as needed" basis, usually specifying the resource
by type and either ID number or name. Since resources can be contained in
files separate from the programmer's CODE resource, many programmers keep
their code size minimal by referencing resources in the System file.
Resource types are distinguished by their four-character labels. Apple has
reserved all resource type names which consist of lower case or international
characters (ASCII $61-$7A and $7F on up). Additionally, Apple reserves the
resource type names in the article "Macintosh: Reserved resource type names".
You can make alterations to discrete resources outside of the programmer's
code, customizing or localizing the resource with foreign language prompts,
currency formatting and other custom representations. Use ResEdit, REdit, and
these tools' accompanying documentation, available through the Apple Programmer
Development Association (APDA), to individualize almost any application or to
edit custom-programmed resources.
For sources of information about the Resource Manager and resources in
applications and in ROM, consult Inside Macintosh, volumes I-IV. Chapter 5,
volume I and chapter 3 volume IV pertain directly to the Resource Manager.
For information about resources used by the DeskTop file, read Apple
Macintosh TechNote #29, "Resources Contained in the DeskTop File."