Rega P9 specs Re: spacers

Hi: could anyone tell me if the Rega specs on spacers are a good starting point to tell how many spacers I will need with a certain cart.

For instance Rega says their carts are 14 mm. Therefore if I have a cart that is 16 mm I would need one 2mm spacer. If I have a cart that is 19 mm I would need a total of 5 mm in spacers.

Is this is correct? If so, does anyone know if the height measurment is to be taken with the cart,mounted on the arm, and sitting on a record (i.e suspension engaged) or if the measurment should be taken without the action of the suspenion. I guess the question here is: does anyone know how rega get the 14 mm measurment, so that I can measure potential new carts the samy way, and gauge the spacer requirements.

Also, how do I short list potential carts for the RB1000 tonearm with regards to calculating resonance frequency. I cannot find specs for effective mass on this tonearm.

I'd appreciate it if any P9 owners out there could give me some tips on using this table with anything other than a Rega cart.