Das folgende ging an die falsche liste...
Grüsse Robert
---------- Forwarded message ---------- From: Robert Ribnitz robert.ribnitz@gmail.com Date: Sat, Sep 17, 2011 at 2:00 PM Subject: PDF Readers... To: switzerland@fsfeurope.org
Hello there, here's a tentative list of what PDF supports, and what therefore a PDF reader must also support:
- Passwords/Encryption and digital signatures (MD5, RC4,AES, SHA-1, SHA-256, SHA-384, SHA-512 and RIPEMD160) - Interactive elements (checkboxes, radiobuttons), "fill-in forms" (as in text lines & text boxes) - embedded file streams ("attachments") of any type - ICC and DeviceN color spaces, several of the features present in Postscript Level 3 - Annotations - Masked images, images with alternate representation, smooth shading, transparency - Unicode charaters - import content from one PDF into another - PCKS #7 support with SHA-1 and RSA signaures - Use of usage rights does not require encrypting the document - Possibliity to hide/show sections of text, or review them - JavaScript support - Support for Universa 3D and OpenType - Cross-document linking
ISO 32000-1:2008 specifies a PDF version (PDF 1.7, as supported by Acrobat Reader 8)
The following can be controlled by usage rights:
- Save the PDF, possibly with annotations, form data - Import form data - Export form data
DRM can limit copying, editng, annotations or printing; the use of DRM does not require document encryption.
see http://en.wikipedia.org/wiki/Portable_Document_Format
If we want to give users a chance of using an "alternate" reader, we must provide them with one that supports these features (or at least the more common of them).