Adobe ACROBAT 3D Manual page 592

Guidelines for document properties information
When adding data for document properties, consider the following recommendations:
Title
Use a good descriptive title in the Title field. The file name of the document should appear
in the Search Results dialog box.
Information placement
Always use the same option (field) for similar information. For example, don't use the
Subject option to add an important term for some documents in the collection and the
Keywords option for others.
Category names
Use the same word for the same category. For example, don't use biology for some
documents and life sciences for others.
Responsible party
Use the Author option to identify the group responsible for the document. For example,
the author of a hiring policy document might be the Human Resources department.
Part numbers
If you use document part numbers, add them as keywords. For example, add doc#=m234
to the Keywords option to indicate a specific document in a series of several hundred
documents on a particular subject.
Document types
Use the Subject or Keywords option, either alone or together, to categorize documents by
type. For example, you might use status report as a Subject entry and monthly or weekly
as a Keywords entry for a single document.
If you already have specialized training in Adobe PDF, you can define custom data fields,
such as Document Type, Document Number, and Document Identifier, when you create
the index. This is recommended only for advanced users and is not covered in Acrobat
Complete Help.