6. A process as claimed in claim 4 wherein said modes include a mode in which passage of said expanded code to said output file is inhibited by presence of said parameter in said source code statement.
4. A process of modification of source code developed for an origin system of known dialect, to produce source code for use in a destination system of differing from dialect, comprising the steps of: (a) providing a source file containing said source code, comprising a plurality of sequential source code statements incorporating parameters and macro names, each said macro name representing code to accomplish at least one basic function for data file manipulation including merge, update, extract, summarize and sort; and providing an empty output file; (b) providing said computer with a library file containing a plurality of sequential entries, each said entry comprising a macro name, one or more model statements, each said model statement comprising an expanded code statement which may incorporate one or more parameters, and a number of triplets each corresponding to one of the parameters in said expanded code statement, each said triplet specifying a condition of presence or absence of said corresponding parameter in a source code statement which inhibits passage of said expanded code to said output file; (c) sequentially fetching a source code statement from said source file, and initializing said library file; (d) sequentially fetching an entry from said library file, and comparing said macro name of said entry with said source code statement; (e) repetition of step (d) until said library file is exhausted and, if no macro name is found in said source code statement, passing said source code statement to said output file and reversion to step (c); (f) if said macro name of said entry is found in said source code statement, then sequentially fetching a model statement from said entry; (g) sequentially fetching a triplet in said model statement and a corresponding parameter in said expanded code statement of said model statement; (h) examining said source code statement for presence of said parameter; (i) repetition of steps (g) and (h) until said triplets of said model statement are exhausted and, if each said triplet does not inhibit passage of said expanded code statement to said output file, then passing said expanded code statement to said output file; (j) repetition of steps (f) through (i) until said model statements of said entry are exhausted; and (k) repetition of steps (c) through (j) until said source code statements are exhausted.