Wires are defined by the coordinates of the wire centers. You should read the "Closely Spaced Wires" and "Other Wire Considerations" topics in the "Help" file.
See the 5th question, about half-way down the page, here. Is it worth it? If you go with the standard version you may regret the 500 segment limitation and the lack of a double-precision engine. And a year or two from now, will you even remember or care about the initial cost difference? Dan, AC6LA
Please try 4nec2 first. It's free, and no silly limits on wires and segments, etc. There is no version of eznec I'd pay anything for. Seriously.
Thanks, Dan. I'm using v.4 currently. The only thing I lack there is Hybrid Coupler option. Someone gonna make me a gift, bying v.6 and asks me what version to order. Let it be v.6+ then As for 4nec2 I have one and use it but do not like the interface. Got blunders many a time.
And no guidance of the pitfalls of incorrectly segmenting wires and structuring your models. It is easy to generate beautiful plots of badly constructed models in 4nec2. If you follow Lewellen's and Cebik's guidance distilled into the EzNec help and error checking, you will get a model that better matches the real antenna after you build it.