What interface need to be implemented for attachments?

[tomer]

Hi,
The following is an excerpt from MSDN


"objAttachments.Add(Source, [Type], [Position], [DisplayName])

objAttachments Required. An expression that returns an Attachments
collection object.

Source Required Variant. ........or item that constitutes the attachment.

"

So i wonder what interface should the object need to implements in order
that it can be passed as the first parameter?

Thanks in advance.