PPRF (0x50505249)       /* Page preferences */

The PPRF chunk contains preference settings for ProVector.  Although this
chunk is not required, its use is encouraged because it contains some
important environment information.

        struct PPRFstruct {
            ULONG       ID;
            ULONG       Size;
            char        Prefs[Size];
        };

DR2D stores preferences as a concatenation of several null-terminated
strings, in the Prefs[] array.  The strings can appear in any order. The
currently supported strings are:

                Units=<unit-type>
                Portrait=<boolean>
                PageType=<page-type>
                GridSize=<number>

where:
                <unit-type>   is either Inch, Cm, or Pica
                <boolean>     is either True or False
                <page-type>   is either Standard, Legal, B4, B5, A3,
                                  A4, A5, or Custom
                <number>      is a floating-point number

The DR2D FORM does not require this chunk to explicitly state all the
possible preferences.  In the absence of any particular preference string,
a DR2D reader should fall back on the default value.  The defaults are:

                Units=Inch
                Portrait=True
                PageType=Standard
                GridSize=1.0