valid Input

Use regexmatch(). It will be useful to achieve your requirement.

It really kinda depends on what valid input(s) you're trying to accept.  If you're after only decimal values, you could wrap your save in "todecimal()" at save time, forcing any extraneous characters to go away.  If something like "10.2.3.6.8.9" would be acceptable though, you'd need to check the text manually - a regex would work, but also you could just use built-in functions like "cleanWith()" i.e.
validations: {
  if(ri!text <> cleanWith(ri!text, "0123456789."), "Invalid Characters Entered", null())
}