| Standard Features of PDF 1.4 |
Explanation of Features in PDF/A |
| Identification |
Required PDF/A identifier specifying version and conformance level. |
| Metadata |
Must be XMP-compliant, XMP extensions must embed their descriptions. |
| Logical structure |
Level A: Must be tagged PDF describing structure and semantics. |
| |
Level B: No requirements. |
| Encryption |
Prohibited. Must be possible to open and render without password. |
| Color |
All colors must be identified, e.g. by ICC color profiles. |
| Transparency |
Prohibited. The visual appearance of transparent objects stacked on top of each other is not |
| Layers |
Optional content layers are prohibited. |
| Compression |
LZW compression is prohibited. JPEG 2000 compression is prohibited (not part of PDF 1.4). |
| Fonts |
All fonts must be embedded, except they only appear in rendering mode “invisible”. |
| |
The mapping of character codes to glyphs must be unambiguous. |
| |
Only fonts that are legally embeddable for unlimited, universal rendering shall be used. |
| |
Level A only: Requires a map to Unicode. |
| Annotations |
Static text/label-style annotations allowed, others e.g. movies or sound are prohibited. |
| References |
References to external images or external page content are prohibited. |
| Alternate images |
Alternates for lower resolution display are prohibited. |
| Programming |
Embedded JavaScript is prohibited. |
| Actions |
Certain actions like opening movies or sending forms are prohibited. |
| Forms |
Restricted. See [4] for details. |
| 3D objects |
Prohibited. |
| Postscript |
The embedding of postscript is prohibited. |
| Digital signatures |
A PDF/A-1 conforming way to add digital signatures is possible. |
| |
|
| |
|
| |
|
