PHP also offers a number of well-defined APIs for features such as XML transforms and on-the-fly generation of images and Adobe Portable Document Format (PDF) files.

PHP还提供了许多定义良好的API，用于xml转换之类的功能，以及图像和Adobe可移植文档格式(Portable Document Format, PDF)文件的实时生成。

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Xpdf is an open source Adobe Acrobat viewer for Portable Document format (PDF) files (because so much online information is sitting in PDF, a PDF viewer is almost like a second browser).

Xpdf是一个开放源码的Adobe Acrobat查看器，用来显示pd f (Portable Document Format)文件(因为有太多在线文档都是pdf格式的，因此pd f查看器几乎就成了第二浏览器了)。

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Portable Document format (PDF) files have increasingly been used as a means to deliver spammers' advertisements, but only rarely has the file format been used as an attack vector.

PD F文件已被越来越多地用来作为一种手段来运送垃圾邮件广告，但只有少数的文件格式被用来作为一个攻击向量。

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It's a fax with fidelity, like Adobe Acrobat portable document files without needing a computer.

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