One aspect of the practice change was a reversal in the UKIPO practice concerning computer program claims. For several years previously, the UKIPO had allowed claims directed to a computer program if the method performed by the computer program was itself patentable. In light of the first step of the Aerotel/Macrossan four step test, to construe the claim, the UKIPO decided that claims to a computer program were not a permissible form of claim even if the underlying method was found to be patentable.