PDFlib TET PDF IFilter 4.0 Manual

2.3 PDF Versions and Protected Documents
PDF versions. TET PDF IFilter accepts all PDF versions up to PDF 1.7 extension level 3,
the file format of Acrobat 9. This includes various PDF-based ISO standards, e.g. PDF/A,
PDF/E, and PDF/X. Note that ISO 32 000 is technically equivalent to PDF 1.7 and therefore
also supported.
Protected PDF documents. TET PDF IFilter indexes text and metadata from all documents
as long as it can open it. This includes the following kinds of PDF documents:
> Unencrypted documents;
> Documents which are encrypted with a master password, but do not require any
user password. The status of Acrobat’s security setting Content Copying Allowed/Not
Allowed does not affect documents in this group.
At first glance the second category may look like a violation of the document author’s
intention for protecting the document. However, it is not, since TET PDF IFilter does not
provide any means for actually copying the text; it merely helps the search engine with
indexing the document and subsequently locating the document in a search. Once the
document is identified in a search and opened in Acrobat, it is still subject to any restrictions
regarding content copying which may have been specified for the document.
Encrypted PDF documents which can not be opened will be logged. This category includes
the following cases:
> Encrypted documents which require a user password, i.e. those which cannot be
opened in Acrobat without supplying the corresponding password.
> Documents which have been encrypted with a user-specific security certificate.
Damaged PDF documents. PDF documents may contain damaged data structures, either
because of faulty PDF generation software or because of some accidental modification
(e.g. caused by failed network transfer). TET PDF IFilter automatically detects damaged
PDF documents and attempts to repair such documents in order to allow for
successful extraction of text and metadata. This repair mode will be run automatically
as part of the indexing process. In some cases this mode will not be sufficient, and TET
PDF IFilter will therefore process the document with a more thorough repair mode.
Since it is more time-consuming, this forced repair mode is only applied for severely
damaged PDFs which cannot successfully be processed in automatic repair mode.
If a document can be opened successfully, but contains one or more damaged pages,
these pages will be ignored and processing continues with subsequent pages. For each
ignored page an entry will be written to the application event log.
2.3 PDF Versions and Protected Documents 27