waitfornottext not present in selenium rc

I am testi开发者_高级运维ng using Selenium RC but most of the waitforNottext etc are not present in it. Any idea why?

Am I missing something

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If you use java and Selenium RC then can change condition to negation i.e. -

while(count>0)
 if(!selenium.isTextPresent("text")) {
  Thread.Sleep(1000)[
 }
 count--;
}