Package File

The standard file archive for SimCity 2013 is the package file. Archives of this type contain 3D model information, textures, character information, sounds, and other game data included in the game simulation.

A package file can be likened to a a .zip archive or a compressed folder; it contains a large number of files (sometimes compressed) in a single file on disk. Package files can be opened, extracted, and combined with other package files to group and organize files for easy storage and separation. SimCityPak is a free package file editor specifically designed for SimCity 2013.

Index
Every file in a package is identified by a unique index. The index is a pointer that counts both as an identifier for the game to refer to specific files and a pointer to a location in the package that contains the actual data for this index. Each index is defined by a Type, Group and Instance ID (TGI).

The combination of TGI identifiers needs to be unique for each index. There are many existing indices with the same Instance ID, but with different Type and Group IDs. In most cases, this means that these indices are related to one another.

Type ID
Specifies the type of file. Denotes whether an index is a 3D model, property file, javascript file, image file, or other type. Some types of files found in a package file are:
 * Property File
 * RW4 (RenderWare) File
 * RASTER File
 * Javascript File
 * Grayscale Map (16 Bit)
 * GIF File
 * Cursor File
 * HTML File
 * JPG File
 * JSON File
 * PNG File
 * TGA File

Group ID
Used to group together like indices. In many cases, this ID is empty. Normally, you should not edit the group ID of an existing index file.

Instance ID
The main identifier for each index. In a lot of cases, the type and group ID aren't even included in a reference to a specific index.