What part of speech is the phrase "Notwithstanding the foregoing?"

In a contract document I'm reading, I found the following sentence:

Notwithstanding the foregoing, your employment is also subject to the following terms:

My question concerns the phrase, "notwithstanding the foregoing." I understanding the meaning, but if you were going to construct a sentence diagram, what part of speech would this phrase have?

My initial reaction was to call it a nominative absolute, but it doesn't seem to fit the usual test (ie, try to subordinate by adding a conjunction + verb of being).

Notwithstanding is a preposition that means in spite of and the noun foregoing is an object of the preposition. Therefore, "Notwithstanding the foregoing" in the sentence is just a prepositional phrase that modifies the sentence.

I think the confusion came from the fact that the preposition notwithstanding is in the form of a present participle (-ing) and the comma placed after the noun foregoing.

The comma is necessary to separate a rather long prepositional phrase from the sentence that follows it.

As you mentioned, there is no verb in the phrase and adding a conjunction doesn't work. Therefore, it is not a nominative absolute or participial construction.