about openoffice PixelFilter?

[zhaojianli]

in main\binfilter\bf_svtools\source\filter.vcl\filtersvt_FilterConfigCache.cxx

const char* FilterConfigCache::FilterConfigCacheEntry::InternalPixelFilterNameList[] =
{
IMP_BMP, IMP_GIF, IMP_PNG,IMP_JPEG, IMP_XBM, IMP_XPM,
EXP_BMP, EXP_JPEG, NULL
};

const char* FilterConfigCache::FilterConfigCacheEntry::InternalVectorFilterNameList[] =
{
IMP_SVMETAFILE, IMP_WMF, IMP_EMF, IMP_SVSGF, IMP_SVSGV,
EXP_SVMETAFILE, EXP_WMF, EXP_EMF, EXP_SVG, NULL
};

const char* FilterConfigCache::FilterConfigCacheEntry::ExternalPixelFilterNameList[] =
{
"egi", "epn", "icd", "ipd", "ipx", "ipb", "epb", "epg",
"epp", "ira", "era", "itg", "iti", "eti", "exp", NULL
};


my question as below:

The openoffice division what based InternalPixelFilter or ExternalPixelFilter?
I wrote an addon extension used to insert a new type of picture is to belong InternalPixelFilter or external ExternalPixelFilter?