Yup...every mfr does. See page 8 Part # 253 in the Raritan PHII owners manual.
PH II Owner’s Manual
Part #11 on page 3 in the Jabsco 37010 electric toilet "manual"
http://www.xylemflowcontrol.com/file...43000-0612.pdf
Those are just two examples...Any of y'all who want to can look up more toilets.