Adobe ACROBAT 3D Manual page 590

Guidelines for cross-platform indexing compatibility
When you create files that may be used or distributed through a server using another
platform, long file names can become truncated. This can make it more difficult for users
to find information or identify appropriate files. Although Adobe Acrobat has a
sophisticated mapping filter for identifying the formats of indexed documents,
unnecessarily complex file names can slow down searches or even prevent documents
from being located.
Consider the following guidelines when you name files, folders, and indexes for your
indexed collection.
DOS conventions
The safest approach is to use MS-DOS® file-naming conventions for folder names (8
characters or fewer).
OS/2® LAN Servers
If you are using Mac OS with an OS/2 LAN server and if you want to be sure that the
indexed files are searchable on all Windows platforms, either configure LAN Server
Macintosh (LSM) to enforce MS-DOS file-naming conventions, or index only FAT
volumes. (HPFS volumes may contain long unretrievable file names.)
Single platform
If you index Adobe PDF documents with long file names that will be truncated for
Windows use, work exclusively in either Windows or Mac OS when you build or update
the index.
Folder structure
If you create documents that will be searched only by Mac OS users, do not use deeply
nested folders or path names longer than 256 characters.
Disc delivery
If you are planning to deliver the document collection and index on an ISO 9660-
formatted disc, you should use ISO 9660 file names.
Extended characters
Avoid using extended characters, such as accented characters and some non-English
characters in the names of files and folders for the index or the indexed files. The font
used by the Catalog feature does not support character codes 133 through 159.