ld1 = DATE()
ld2 = DATE()+0.25
? ld1
? ld2
? ld1 = ld2

If you look at the screen output, both date values seem to be equal. Yet, the equals to operator returns .F. ld2 has an invisible time portion of "06:00" which you would only see when you cast the date into a datetime value:

? Dtot(m.ld2)

To make this more confusing: When you store ld2 in a date field and read it back, the time portion is lost and suddenly ld2 equals ld1. Of course, you won't write code that adds 0.25 to a date value intentionally. In real code this bug creeps up in a more evil way. Consider you are calculating the end date of a process. This might involve fractions if the duration is something like 3 days at 80% capacity. So you might end up with:

? Date()+0.9999999

which still prints the current day. If you store this value in a table, your process finishes one day early. A similar problem is adding fractions repeatedly, because you need the end date of a process that consists of multiple steps with a finite but fractional duration.

If you perform date operations by adding values, make sure you use ROUND(nValue,0) for any numeric value. Or convert the date into a datetime variable.