Battery capacity in Amp-hours is written as C. This notation is most useful when talking about charging/discharging rates.
Note: most deep cycle manufacturer's rate capacity at C/20, due to Peukert effect.
If you have a 200AH battery bank then C = 200AH.
If the manufacturer recommends max charging at C/5 the rate should be at or below 40A (200/5).
If the manufacturer recommends minimum charging at C/10 the rate should be at or above 20A (200/10).
If the manufacturer recommends max discharge (load) be 3C the rate should be at or below 600A (3×200).
If the manufacturer says that Absorption stage is complete when charging current has dropped to C/100 or C/200 then the current to watch for would be 2A (200/100) or 1A (200/200).