There is a Ferricyanide bleach which requires 2 extra steps (clearing baths) or a Ferric EDTA bleach which is the current E6 bleach. Both work.
The Ferricyanide Bleach is a regular rehal bleach found here on APUG and the clearing bath is a Sodium Sulfite stop with 1 - 2$ Acetic Acid.
The EDTA bleach is Ferric Nitrate + Ammonium Chloride + EDTA. The pH is adjusted to about 6 with Ammonium Hydroxide and Acetic Acid.
As you can see, the Ferri bleach uses more readily available chemistry.
PE