When filing a case with the Central Administrative Tribunal (CAT), it's crucial to understand the signing requirements for your Original Application (OA) and its annexures. You must sign all pages of the OA and all annexures in original for every set filed with the court. Additionally, the verification section of the OA needs to be signed and duly attested by an Advocate or Gazetted Officer, and all annexures must also be attested. Ensure you provide two signed copies of each page, with the total number of copies being two plus the number of respondents.