The limit can be in one of these formats:

- A number, which specifies a prime limit. If it isn't a prime, you get the next lowest prime.
- A list of partials separated by dots. For example, 2.3.5.7.11 for the 11-limit. Whether these are prime numbers or not, they become the prime intervals. You can also include fractions, for example 2.3.11/2.7 is a 7-limit with 11/2 replacing 5.
- Overtone numbers for a chord separated by colons. For example, A strange way of writing the 7-limit is 4:5:6:7:8 where you have to remember the 8 or octaves aren't included.
- A list of numbers in cents separated by spaces. For example, the 7-limit could be written as 1200.0 1902.0 2786.0 3386.0 if you really wanted to.

The target error is a parameter that determines the badness of the temperaments you get out. The formula is Ek = e/log2(L) where e is the error and L is the largest prime in the limit you chose. There's no expert's mode for providing Ek directly because experts should be able to reverse engineer this formula.