The part you're asking about is a regular expression (often shortened to regex or regexp). Look up rexCompile() or Google for details.
What Dave has shown will accept only: an optional negative sign, zero or more integers, a optional period, and then one or more integers. This will capture any positive or negative number (integer or float).
To accept only the 4 numbers you've shown, I think PCRE is simpler. Replace rexMatchp(...) with pcreMatchp("^[1-4]{7}.[1-4]{2}$" nStr). This will accept only: 7 integers between 1 and 4 in any order, a mandatory period, and 2 more integers between 1 and 4 in any order.
Once you figure out how a regex works, it'll be simple to extend the code to accept exactly the 4 numbers you posted. I didn't do this because you typed "at least", so I take it there might be further changes required to accept numbers other than the 4 you listed above and I don't know what that might be.
All the tools have been given to you within this thread. Take a few minutes to digest what's been posted, snoop around in the SKILL documentation and online, and you can figure it out. Then you'll be able to modify the regex yourself instead of asking for the answer. There are many smart and helpful people here, but there's nothing like figuring it out for yourself.