Battery capacity in Amp-hours is written as C. This notation is most useful when talking about charging/discharging rates.

Examples: If you have a 200AH battery bank then C = 200AH.

If the manufacturer recommends max chargign at C/5 the rate should be at or below 40A (200/5).
If the manufacturer recommends max charging at C the rate should be at or below 200A (200/1).
Note: the usual charge rate for deep cycle batteries is C/10. Sometimes manufacturers express that Absorption stage is complete¹⁾ when the bank is holding Vabs with C/100 or C/200 of current.

If the manufacturer recommends max discharge (load) be 3C the rate should be at or below 600A (3×200).
Note: most deep cycle manufacturer's rate capacity at C/20, due to Peukert effect.