Comment by mananaysiempre

Just as a side note, there are two versions of tiff6.pdf (titled “TIFF, Revision 6.0, Final — June 3, 1992”) on the ’net: one[1] that mentions Aldus on the title page and one[2] that mentions Adobe. Only the Aldus one has the invisitext. (Curiously, the metadata says it’s newer.)

[1] SHA256: dbcdf729182937ecff415dfd06806894bf03bfd741291aa3ad7ba45335673def, modify date 2002-05-10, created by Acrobat Distiller 4.05 for Windows, e.g. https://www.itu.int/itudoc/itu-t/com16/tiff-fx/docs/tiff6.pd...

[2] SHA256: 8cb1e1a2226e423ba8b88f57366a30ef1b7ad6109443ebdda072b952739a8d76, modify date 1995-09-14, created by Acrobat Distiller 2.1 for Power Macintosh, e.g. https://download.osgeo.org/libtiff/doc/TIFF6.pdf