Conversion psig/psia to psi
From a mechanics view, I'm talking shipboard mechanics now. We always said PSI, meaning gage press. The only time we used psia as a term, was dealing with steam pressures. Which is kinda it's own world.
So for your basic fluids: Water, Oil, Service Air, Industrial Gas (in a big ole welding bottle or freon) we just said psi.
Whatever you decide, everybody in the shop needs to be reading off the same sheet of music. I'm guessing if your operating at 900 pounds it's either Hydraulics, Industrial Gas or High Pressure Air.
So just tell 'em it's reading 900 pounds and then have some coffee.