If you use IBM CICS Transaction Gateway, you can supply information that enables data to be converted in data conversion templates, which are held in an indexed file called dfhdrcnv, in the same folder as the resource definition file (by default ). Each data conversion template contains entries for resources that need translation and identifies which data fields require it. Each resource must have an entry in the resource definition file.
You cannot edit the file dfhdrcnv directly; instead you maintain it by importing mainframe-style DFHCNV macros, and by deleting templates that you no longer need.
Mainframe-style DFHCNV macros are organized into entries and templates. An entry is a set of conversion macros that apply to the same resource; the start of an entry is marked by a DFHCNV macro that begins TYPE=ENTRY and the entry continues until the next macro that begins TYPE=ENTRY, or until the END marker. An entry can contain one or several templates, depending on the type of resource it belongs to.