Like Caped said, it depends on what the requirement is. I find it best to make judicious use of the "New (Copy)" button (at the bottom of the list where you would add an Edge) to look at examples of other Edges that have pre-requisites, preferably of the same type I need to use. So, for example, for a Trait you could take a look at the Ace edge which needs Agility d8+. On that one you can see the "Expr-Reqs" button (in the buttons on the left) is highlighted and has a "x1" next to it. That just means there is an "Expression Requirement" for the Edge.
Click on the Expr-Req and you'll see a few things that it does' Under "Message:" is the text that will be displayed in Red if a character doesn't meet the requirements for that Edge. Then there are some check-boxes which you don't normally need to mess with. Then the actual Code on the "Pre-requisite Expression" line. In this case "#trait[attrAgi] >= 4" It's important to remember that for Savage Worlds files the die type is halved into a numeric value, so a d8 is listed as a 4, d6 would be 3, and so on.
That "#trait" part is actually a kind of macro, or shorthand, for a longer piece of code. The important thing to know about it is that you would use it when you KNOW a character will have what you are looking for. All characters have Traits so you are fine using it like that here.
For Skills, however, there is no guarantee that a character will even have the skill to check against the number. So for that check out something like the Adept edge. Again you've got another Expr-Req (2, this time) and one of this is for a Skill, Faith. So this time the code looks a little different, "#traitfound[skFaith] >= 4". That "#traitfound" part is the macro here, rather than "trait". You use traitfound when the trait might not exist on any given character, like for skills.
You'll notice there that the "Pick-Reqs" button is also highlighted for Adept. If you click on it you'll see that this is what you fill in when an Edge requires some other Edge, for example. That one is pretty simple to use.
The special cases tend to do with things like Knowledge skills (since those can jsut be filled in by hand) and there are examples of some of the more complex things to look for an do in the
"Common Codes" thread stickied at the top of this forum. That thread also has some pointers for where you can get more information in the program and on the Hero Lab Wiki for how to do things in the Editor.
Hope that helps!
Lenny
