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       CHAPTER 9                                                           Multimedia Features




                       TABLE 9.10 Entries in a media permissions dictionary
KEY      TYPE          VALUE

Type     name          (Optional) The type of PDF object that this dictionary describes; if present, must be
                       MediaPermissions for a media permissions dictionary.

TF       ASCII         (Optional) An ASCII string indicating the circumstances under which it is accept-
         string        able to write a temporary file in order to play a media clip. Valid values are:
                          (TEMPNEVER)       Never allowed.
                          (TEMPEXTRACT) Allowed only if the document permissions allow content
                                            extraction; for example, when bit 5 of the user access
                                            permissions (see Table 3.20) is set.
                          (TEMPACCESS)      Allowed only if the document permissions allow content
                                            extraction, including for accessibility purposes; for example,
                                            when bits 5 or 10 of the user access permissions (see Table
                                            3.20) are set, or both.
                          (TEMPALWAYS)      Always allowed.
                          Default value: (TEMPNEVER).
                          An unrecognized value is treated as (TEMPNEVER).

       The BU entry in the media clip data MH and BE dictionaries (see Table 9.11) spec-
       ifies a base URL for the media data. Relative URLs in the media (which point to
       auxiliary files or are used for hyperlinking, for example) should be resolved with
       respect to the value of BU. The following should be noted about the BU entry:

       • If BU is in the MH dictionary and the base URL is not honored (for example, the
         player does not accept base URLs), the media clip data is non-viable.
       • Determining the viability of the object does not require checking whether the
         base URL is valid (for example, that the target host exists).
       • Absolute URls within the media are not affected.
       • If the media itself contains a base URL (for example, the <BASE> element is de-
         fined in HTML), that value is used in preference to BU.
       • BU is completely independent of and unrelated to the value of the URI entry in
         the document catalog (see Section 3.6.1, “Document Catalog”).

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