We were faced with quite a few constraints at the time, mostly due to practical reasons.
There was only a 14.4 baud modem to serve as a point-to-point connection between the pharmacies, wholesalers, and owners.
The National Health Insurance required their reporting in the form of floppies. These had to be generated as two identical sets of 1.44 MB floppies in a signed envelope. The floppies were so unreliable, sometime even 2 sets were not enough.
Must be cheap
Since the system was to replace already established systems, it had to cost even less than those. It also meant, that could not use any commercial software, that required per site or per computer licenses.
Reuse existing hardware
Just like above. The original concept was to reuse whatever the pharmacy already has, and only upgrade whatever is necessary. The system had to run on clients with i286 (16bit) with as low as 640KB of ram and support a number of different network cards. The only hardware we could not reuse was the “black-box” that stored the transaction details for the tax authority.