modify: "non-existant attribute"

["Jim Sermersheim" <jimse@novell.com>]

In section 4.6 of RFC 2251, the replace semantics state: ""A replace ... is ignored if the attribute does not exist."

What does "does not exist" mean?
1) The attribute is known (in the schema), and valid for this entry (in the object class), but no values currently exist. (no, because previously it says "creating the attribute if it did not already exist").
2) The attribute is known (in the schema), but is not valid for this entry (not in the object class).
3) The attribute is not known (not in the schema at all).

Also, should similar language be applied to the delete semantics? (ignore unknown attributes)

Jim