The UPSC (Union Public Service Commission) has specific rules regarding tattoos for candidates appearing for the civil service exams. According to the UPSC's physical standards for candidates, tattoos that are visible while wearing the prescribed uniform should be "restricted to the inner aspect of the forearms and should be at least half an inch below the elbow joint." Candidates who have tattoos on other parts of their body will not be permitted to appear for the exam. It's important to note that these rules only apply to candidates appearing for the UPSC civil service exams. Different organizations may have different rules regarding tattoos.