. . . AutoNumbers should *never* be
seen by the user or used for anything
but a unique number field in a table
The reason for this is that users (and some developers) expect AutoNumbers
to be consecutive, increasing values, incrementing by 1. They often
(usually) are, but if one starts to create a new record, then cancels, the
autonumber is lost (never used), and there are other circumstances that can
cause gaps in the sequence.
Wanting the autonumber to start at a particular number implies that you may
have expectations of this kind. And, as Rural Guy said, they should only be
used as a unique identifier, because they are only expected to be unique,
not always a "monotonically increasing series".
Larry Linson
Microsoft Access MVP