An applied-for gTLD string can be found invalid for many reasons. These include not being within the specified length, not conforming to IDNA2008, not complying with RZ-LGR, etc. If the applicant believes the TLD Application Management System (TAMS) made a mistake in flagging the applied-for string in the DNS Stability Review, the result can be challenged. An applicant must submit the challenge no later than 14 days before the close of the application submission period. ICANN will then review whether there was a system error. This challenge mechanism only applies to strings using scripts supported by the applicable version of the RZ-LGR.
When TAMS applies RZ-LGR on the primary string, it can flag a variant string as 'blocked.' Similarly, if the applicant believes that the tool has made a mistake, it can submit the challenge no later than 14 days before the close of the application submission period. ICANN will then review whether there was a system error.