2000A/TRN02 element note states that its value "must be unique on a per attachment basis" when submitted as unsolicited 275 (BGN02 = '02').
Does this mean that each loop 2000A always represent a single and complete attachment and TRN02 must always have unique values within unsolicited 275 transaction?
For an unsolicited 275 (BGN01 = ‘2’), the 2000A Loop TRN02 must contain the Attachment Control Number from the PWK06 of the 837 claim, and the value must be unique per attachment. Therefore, each iteration of the 2000A Loop with a unique Attachment Control Number in the TRN02 would always represent a separate attachment.