Could anybody diagram this sentence?

"What a most delightful quatrain Jamie has written."

Where would the placement of the word "What" go in the diagram?

I believe "what" is an interjection in this sentence.

http://www.thefreedictionary.com/what

It should be on a horizontal line above the subject.

http://www.english-grammar-revolution.com/interjections.html

In the sentence "What a most delightful quatrain Jamie has written," the word "What" would be diagrammed as an interjection or exclamation. It would be placed at the beginning of the sentence, before the subject "a most delightful quatrain Jamie has written."

To diagram the sentence "What a most delightful quatrain Jamie has written," you can use a modified form of a sentence diagram called a question diagram. In a question diagram, the subject and verb are still placed on the baseline, but the question word is placed to the left of the subject.

Here is an example of how the sentence could be diagrammed:

-
| |
| |
| |
| |
________| |________
| |QT | |
| What |__________|
| QP |
|________________|
| | | |
| Have | | Written
|________| |_________
| VP |
| |VRB |
-|---------------------|
| | | |
| Jamie| NP " |
|______|_____|___

Here, "What" is diagrammed as the question word (QW) connected to the Subject Phrase (QP) "a most delightful quatrain Jamie has written." The rest of the sentence is diagrammed as usual, with the verb phrase "Have Written" connected to the subject phrase by a verb (VRB) line, and the object phrase "Jamie" connected to the verb phrase by a noun phrase (NP) line.