Flags for packageType of AT_PDE_FONTATTRS.
Values:
| IG_PDF_SYSFONT_UNKNOWN | 0 | Unknown. |
| IG_PDF_SYSFONT_TYPE1 | 1 | Type1. |
| IG_PDF_SYSFONT_TRUETYPE | 2 | TrueType. |
| IG_PDF_SYSFONT_CID | 3 | CID. |
| IG_PDF_SYSFONT_ATC | 4 | ATC. |
| IG_PDF_SYSFONT_OCF | 5 | OCF. |
| IG_PDF_SYSFONT_OPENTYPE_CFF | 6 | OpenType CFF. |
| IG_PDF_SYSFONT_OPENTYPE_CID | 7 | OpenType CID. |
| IG_PDF_SYSFONT_OPENTYPE_TT | 8 | OpenType TT. |