PDFlib TET PDF IFilter 4.0 Manual

3.2 Metadata Organization
Metadata is organized in the following hierarchical way:
> Properties are the fundamental building blocks for metadata. Properties in the Windows
operating system and the IFilter interface are organized by a unique numeric
identifier (see below).
> Property sets comprise a group of properties which usually have some logical relationship.
All properties in a set share the same GUID (see below). Property sets can be
specified in the XML configuration file.
> Property set collections comprise a group of property sets. TET PDF IFilter implements
several predefined property set collections. They can be used to collectively enable
or disable multiple property sets together. It is not required to configure additional
property set collections.
Property identification and GUIDs. Properties are identified in the IFilter interface by
an identifier which consists of two parts:
> The first part is the Globally Unique Identifier GUID (sometimes also called Universally
Unique Identifier, UUID), a unique 128-bit identifier which has the same value for all
properties in a property set. Details on GUIDs can be found at
www.itu.int/ITU-T/studygroups/com17/oid/X.667-E.pdf
There are various tools available for creating GUIDs; you can also use online services,
e.g. the one which is available at
www.itu.int/ITU-T/asn1/uuid.html
A sample GUID looks as follows: 7a737220-0cd0-11dd-bd75-0002a5d5c51b.
> The second part uniquely identifies the property within its property set. It can consist
of a positive integer called the identifier, or ID for short. Property identifiers in a
set must start with the value 2, but are otherwise arbitrary. Property identifiers are
supported in all IFilter clients.
Alternatively, the second part may consist of a cleartext name. The use of names instead
of IDs is deprecated, and is not supported by some IFilter clients, e.g. Windows
Search. However, it can make configuration more convenient for those IFilter clients
which support it, e.g. SharePoint. See »XML configuration for GUID+name treatment
of properties«, page 43, for information on enabling the GUID+name method.
The GUID+ID or GUID+name combination is required to configure metadata property
queries in search products. Other aspects of metadata properties are detailed in Section
3.4, »Custom Metadata Properties«, page 42.
40 Chapter 3: Metadata Properties