Posts occur in the following order:

1. AutoOpen Posts
2. Option-0 (Zero) Posts
3. All other Posts — Option 1, 2, 3 and 4 (The order of multiple posts of this type can not be accurately determined and should not be relied upon.

An entry form which uses all three posting types will behave in the following fashion:

The first time you attempt to enter the record, the AutoOpen posts are triggered, opening the view specified in the AutoOpen slot of the post icon. Once that view is entered (and the view auto-closes), the original view is reactivated. However: the first entry event was 'lost' to the AutoOpen trigger, and it takes another entry event (press the Enter key again) to enter the record and trigger subsequent posts. At this point, the Option 0 posts occur, followed by all other post types.

Although not strictly a posting event, a closely related function is available via a defaulted field on the entry view. A defaulted field is one that also contains an abacus that supplies a default value. These defaults are available even before the entry event occurs, effectively happening even before the AutoOpen posts.