The 1x1 fixture carried an IDAT from a different image: its CRC fails and the
zlib stream is truncated. Chromium and WebKit render it anyway, Firefox reports
"Image corrupt or truncated", and the same bytes sat in eleven fixtures.
ODF style:vertical-pos/-rel on an inline frame, which every LibreOffice
formula image carries: baseline, character area, or a plain offset from the
baseline. The default moves from the line-box bottom to the baseline, so a
line with a picture in it keeps the descent below it, as LibreOffice and
Word both do.
Steffen Becker