plumbing plans

I know this probably plumbing 101, but here's my question : I have built several homes myself in the past, and am planning a mother-in-in-law suite / guest house. It's a simple square with 1 bathroom and a "bar sink", so I thought I could draw the plans myself this time. The county is asking me to show a sanitary invert at the 2 way cleanout and HCS. The plans for my other houses only show the 2 way cleanout and the vent thru roof as cleanout. These are new requirements since the last time I built. Please help.

Thanks,
part time builder

invert

The "invert" is the depth of the bottom of the pipe relative to some standard measurement, whether it is a benchmark, or the finished floor level. In other words they want to know how deep it will be.