G.R. No. 159358 6 of 10 http://sc.judiciary.gov.ph/jurisprudence/2009/july2009/159358.htm [10] tribunals to us takes time. For this reason, compliance with the rule on the inclusion of material portions of the record is a critical requirement whose violation leads to the dismissal of the petition. In Eurekas case, the success of its petition largely depends on the Postmasters certification; thus, its failure to attach this material document to its petition or even to its memorandum is fatal to its cause. Without the certification, this Court is left to infer the question of the certifications authenticity, worth and validity solely from Eurekas allegations of its contents. Through the certification, Eureka attempts to prove a positive assertion i.e., that it received a copy of the Labor Arbiters decision on November 22, 1999, and not on November 21, 1999 as stated in the registry return card on record. The basic evidentiary rule is that he who asserts a fact or the affirmative of an issue has the burden of proving [11] it. Since the Postmasters certification is Eurekas only evidence to prove its claim, its absence leaves the Court with nothing to consider in weighing Eurekas assertion. Timeliness of Appeal - a Question of Fact not Covered by a Rule 45 Review. Eurekas petition essentially asks the Court to resolve whether its appeal with the NLRC was filed within the prescribed period. This issue is not a novel one as we have had [12] where we held occasion to rule on this same issue in Mangahas v. Court of Appeals that timeliness of an appeal is a factual issue that requires a review of the evidence presented on when the appeal was actually filed. In a petition for review on certiorari, this Court is limited to the review of errors of law; we do not pass upon findings of facts under this mode of review unless the lower tribunals decision is shown to be attended by grave abuse of discretion, as when they are [13] shown to have been made arbitrarily or in disregard of the evidence on record. This rule applies with great force in labor cases where the ruling tribunal the NLRC exercises specialized jurisdiction and has acknowledged expertise on labor matters; we generally accord the NLRCs findings not only respect but even finality, unless the exceptions mentioned above exist, or when a review of the findings of facts is rendered necessary and appropriate because the factual findings and conclusions of the labor arbiter, the NLRC and 1/28/2016 12:50 PM