Lightman's Currency Trade Rules Guide: Discounts, Sales, Limits and Pricing
Lightman's Currency trade rules give you control over how customers buy from your traders, covering discounts, sales, trade limits, and demand-based pricing. Every rule described here lives in a menu rather than on the trade itself, so the first skill to learn is where each set of options can be found.
Where Trade Rules Live
Rules come in two scopes. Anything meant to affect every offer on a trader is reached through the Trader Rules tab inside the Trader's Storage menu. Anything meant to affect just one offer is reached differently: open that trade's details tab, then press the Trade-Specific Rules button that shows up there.
Discount Codes
The Discount Codes rule supports multiple codes, each tracked and handled on its own. Codes you have already made appear as a list inside the rule's settings, and a text box at the bottom of that list is where you type a new one.
Once a code exists, you set its discount percentage — entering 10, for example, means a 10% discount — and you can go further by defining advanced limitations on it.
Customers have two routes to redeem a code. The first is a 
Coupon: someone crafts one at a 
Ticket Station, entering the code so it matches the Discount Code you created. Anyone carrying a coupon made this way gets the discount applied automatically to every trade they interact with. The second route is simply telling the customer the code; they then click Apply Discount Codes on the Trading Screen and type it in by hand.
Discounts
This rule keeps things simple, with two inputs worth knowing. The text box in the top-left sets the discount percentage, using the same convention as above — 10 means 10% off. Beneath it sits the list of players who qualify for that discount.
Sale
The Sale rule has three inputs worth knowing. As with Discounts, the top-left text box defines the discount percentage, where 10 equals 10%. At the very bottom of the rule is a time input that decides how long the sale runs.
Trade Limits
Two limit-style rules exist, and both share the same core inputs. The first is a limit count: the number of interactions permitted before the rule shuts the trade down. The second is a button that clears the record of earlier interactions, resetting the rule.
An extra timer input is also available. It clears a given player's past interactions once a set amount of time has elapsed. This is useful when stock is scarce — by capping how often one person can buy, you leave room for other customers to get the item.
Demand-Based Pricing
This rule adjusts price according to stock. Its main inputs are the min and max stock fields, which set the lower and upper ends of the stock range. A further price input defines the second price used across that range.
Putting It Together
Scope decides your starting point: Trader Rules for store-wide behavior, the Trade-Specific Rules button for a single offer. From there, pick the rule that matches your goal — codes for trackable promotions, a plain discount for a chosen group, a sale for a limited-time cut, limits to ration supply, and demand-based pricing to shift prices with stock.
Covers the mod’s in-game guide topics: Accessing Trade Rules Discount Codes Discounts Sale Trade Limits Demand-Based Pricing
Ticket