阿元包文件通常被归类为一个压缩文件,而这些元数据包文件都集成了压缩规范专有的苹果,特别是适用于Mac OS X平台开发了Macintosh的安装程序包的小程序。这些元数据包文件也执行与编码标准,再次专有的苹果,用来存储在MPKG格式文件的生成。自解压的功能也被内置到这些元包文件,以便用户只需要执行的MPKG文件,并允许存储在MPKG文件的源代码中提取某些文件和文件夹,并将它们存储在Mac OS X系统的指定目录。这些元数据包文件的内容通常是源代码还是由苹果公司安装的Macintosh安装程序包为Mac OS X的这些可能包括操作系统更新,小升级和修复或补丁开发的算法。在Mac OS X平台,在这些元数据包文件的执行和初始化,引用存储在MPKG文件中的数据和定位包含在Macintosh上安装程序包中的其他程序文件,所以Mac OS X可以存储在特定的文件和文件夹相应的目录和执行其他相关文件,继续与Macintosh安装程序包的安装。
Apple Installer is a system software installer which is already integrated in OS X, or the operating system of Macintosh computers. It has the function to install and extra files of .pkg packages. This installer was first created by NeXT but later maintained and republished by Apple Inc., yet the purpose is still to help developers and creators of software in creating installers for different applications and programs. The versions released by Apple are System 6, System 7.5, Mac OS 7.6, and Mac OS X with distinctive features each. Installer System 6 was a dialogue box so a user could not switch back to the Finder; however, there is a selection of items via the Custom Install. Installer 7.5 was a separate window with windows that are resizable, title bars, info buttons, and hierarchical triangular list view. Installer (Mac OS 7.6) is presently called as the umbrella installer with routine that must be executed. Lastly, the Mac OS X is the centralized program for Mac OS X computers that includes Installer application and to-be-installed software as a package.