The version of the EXIF specification this data is stored at.
Namespace:
Aurigma.GraphicsMill.Codecs
Assembly:
Aurigma.GraphicsMill (in Aurigma.GraphicsMill.dll)
Due specification this field should be always presented at correct EXIF data block. Otherwise it should be treated as corrupted or unsupported by standard. So you should never remove this tag.
To get more details about exact meaning of this field, refer EXIF specification.