CANDAT uses as its Master file the Canadian Food file. This Master file is included with CANDAT. CANDAT can also accommodate a second or alternate Master food file (such as the USDA Handbook #8 file).

1. Food code: The code structure used is identical to that used by the Canadian food file. An extra zero has been added to the end of the 6 digit code to allow the institute and user files to fold new food codes into the same code areas as that of the Master food file.
2. Tier Structure: CANDAT has a three tiered food file structure. The first tier contains the Master food file. CANDAT does not allow direct changes to be made to this file. The next tier contains the Institute file. There is only one such file and CANDAT is installed with this file empty. The third tier contains the User food files. There can be any number of User food files though only one can be active at a time.
   The concept of the three tier system also allows an institution to define values for foods to be used in analysis by all its users. Values the institution may consider less accurate than desired in the Master food file can be entered and used from the Institute food file. The food information is copied completely from the Master file and stored in the Institute file where it can be changed, under password control, by the manager of the system.
   The same concept applies to the User food file in relation to both the Master food file and the Institute food file. When CANDAT needs food information it first looks to the User food file, then to the Institute file and finally, to the Master food file. Identical food codes are used at each tier so that finding the food has the effect of masking the level(s) above it.