Sal,

"The Attachment Sequence Number 56 on IRS Form 8888 is used to refer to specific attached documentation. When you file your tax return and need to provide additional information or details related to your tax refund, the IRS assigns attachment sequence numbers to distinguish the various forms, statements, or schedules you include with your return.

In your case, as a trustee, Attachment Sequence No.56 could indicate that you've attached the 56th set of supporting documents to your Form 8888. These documents may contain information or instructions relevant to the allocation of your tax refund, which is the primary purpose of Form 8888.

It's crucial to ensure that you maintain accurate records of the attachments and that the information provided is consistent with the instructions provided by the IRS for Form 8888. If you have specific questions about the form or the documentation you've attached, you may want to consult a tax professional or the IRS for further guidance."