when it calculated the resulting coefficients in the columns, it was summing coefficients across tiles. In response, the circuit court cited Phillips v. AWH Corp.: "the ordinary and customary meaning of a claim term is the meaning that the term would have to a person of ordinary skill in the art". The court held that there was no evidence that such a person would consider taking a DWT to fall under the "maintaining updated sums" limitation. Claims 21 and later As explained by the circuit court, "claim 21 of the '835 patent is identical to claim 1 except that it does not contain the 'maintaining updated sums' and 'periodically compressing said sums' limitations". The district court decided that the claim did not lead to a seamless DWT because the word "seamless" did not appear in it. The circuit court agreed with LizardTech that claim 21 was directed to creating a seamless DWT, but nevertheless decided that claim 21 was invalid. The circuit court held that claim 21, since it lacked the limitations of claim 1, would need "to cover all ways of performing DWT-based compression processes that lead to a seamless DWT". The circuit court looked to the "written description" requirement of 35 U.S.C. § 112, holding that the '835 patent did not properly describe any method other than "maintaining updated sums". Since the patent failed to give a proper written description for claim 21, the circuit court ruled that claim 21 was invalid. The remaining claims depended on claim 21. See also Extensis, successor company of LizardTech References External links Full text of US patent 5,710,835 United States Court of Appeals for the Federal Circuit cases United States patent case law 2005 in United States case law