I don't recall exactly. This was during the 1970's so please forgive my lack of total recall. As I vaguely recall, it was purchased in 55 gallon drums from some industrial supplier for use in restaurant and cafeteria kitchens. Production later changed to a different product in order to remove the chlorine compounds.
The phosphate alternatives are typically zeolites, sodium carbonate, nitrilo-triacetic acid, and citric acid. There are some other formulations that are being tested or used.
Note that the formulation already has considerable sodium carbonate. The citric acid is where the "lemon fresh" advertising mantra originated. However, in the US, the phosphate restrictions apply mostly to consumer products, because the substitutes don't work as well as the real thing.
Here's a summary of the situation:
Make sure that it includes a surfactant to reduce surface tension. In the dishwasher, it reduces water spots and hard water stains on the dishes and PCB's. It can be added to the rinse while washing. I used only a few drops of Kodak Photo Flo for the purpose: which is:
Propylene glycol 25-30% (anti-freeze)
Octylphenoxypolyethoxyethanol 5-10% (Triton X-100 non-ionic surfactant)
phone call from paying customer... gone.