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Welcome to the SimCity 4 GZCOM Reference. This wiki is intended to serve as a technical reference for programmers who wish to create DLL mods for SimCity 4.

Note that this wiki assumes a basic understanding of C++ and SimCity 4 modding concepts. The following resources are available for more detailed explanations of modding concepts:

• cppreference for the C++ language and constructs
• SC4Devotion Wiki for information on SimCity 4 structures and functionality
• SimsWiki for any information in internal structures in the game that are not referenced on SC4Devotion
  • Note that specific hex instance IDs may not match those in SimCity 4

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Understanding the GZCOM

• Component Object Model
• GZCOM Directors
• The GZCOM Framework
• Services
• Hooks
• Messages

Code Samples

• Dissecting the Sample DLL
• Paul Pedriana's reference code

References

• List of Class IDs
• List of Message IDs
• List of Service Definitions