Hi Seb.
Platform wise we are windows only. Database wise its currently Informix and Oracle, with plans to potentially add SQL Server at some point in the future.
The main functions we use the API for are to give us full control over the format of a datetime (datetime -> string and string -> datetime). These are primarily used in file input/output routines (ASCII, XML, etc) so just about any format of a datetime can be accommodated by just setting up the appropriate mask in a configuration file. I think we also use rdefmtdate() for string -> date conversions with a format mask...