The on-sale date is the date on which the given issue was first available for sale to the general public. It should not be used to record dates on which advance copies were made available (e.g. review or promotional copies or trade show previews).
If only partial information is known about the date you should enter those parts which are known and left the rest empty.
If you only know the decade you can enter the first three digits, e.g. 199 for the decade 1990-1999.
If the entered date information is uncertain a corresponding flag must be set. To be precise, the uncertain flag only relates to the actual entered data, therefore if e.g. no day is entered, but the month and year are certain, the uncertain flag is not set.
- See also Publication Date.