Self Funded Searcher Terms

So there have been a lot of REALLY helpful posts on this topic already and here are two as an example:
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From what I have gathered, a fairly common structure for equity investors in a self funded searched is a "pref", liquidity preference, and an equity step up. Some more great resources:

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My question, can someone help me understand the mechanics of a "pref"? Is this just a coupon payment made on their intial investment? Does this have anything to do with the net income of the business? Does anyone have an excel model of an example deal they can share?



Thank you!