This may be drift, but important to understand IMO:

While what Oliver says is true: a DF Decimal variable is 16.16, it's important to remember that when it comes to table values, DF "translating" an SQL datatype to Numeric (& vice versa), drops it to at most 8 places to the right of the decimal point when saved to the DB. So - 1.12345678999 becomes 1.12345678.

This means storing something with greater precision requires embedded SQL. Don't even think about scientific notation... I recently put together subclasses to get around this (customer needed 1.23e-13) & it was a lot of work.

Then there's the whole "Reals in MS SQL are 'approximate' values thing (MS limitation, not DF) - so you have to store as a Decimal.