Developing/fixing monobath and its use for processing low silver black-and-white photographic elements

A processing kit comprising:

• a) a black-and-white developing/fixing monobath composition that has a pH of from about 10 to about 12.5 and is free of dihydroxybenzene developing agents and ammonium ions, and comprises:
• from about 200 to about 500 mmol/l of an ascorbic acid developing agent,
• at least 200 mmol/l of sulfite ions, and
• from about 40 to about 30 mmol/l of an organic compound having both a thiol group and an amino group as the sole photographic fixing agent, and
• b) a black-and-white photographic silver halide element comprising a support having disposed on each side thereof, a silver halide emulsion unit that comprises silver halide grains and a gelatino-vehicle, said silver halide grains comprising at least 95 mol % bromide based on total silver, at least 50% of the silver halide grain projected area being provided by tabular grains having an average aspect ratio greater than 8, a thickness no greater than 0.10 .mu.m, and an average grain diameter of from about 1.5 to about 3 .mu.m,
• the coverage of silver in each silver halide emulsion unit being no more than 11 mg/dm.sup.2, and the coverage of said gelatino-vehicle in each silver halide emulsion unit being no more than 11 mg/dm.sup.2.