# The Patents (Supplementary Protection Certificates) Rules 1997, Paragraph 2: Definitions


“substances”: chemical elements and their compounds, as they occur naturally or by manufacture, including any impurity inevitably resulting from the manufacturing process;

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Source: https://www.legislation.gov.uk/uksi/1997/64/schedule/1/crossheading/1/paragraph/2 (the official version)
Page: https://openlegislation.uk/patents-supplementary-protection-certificates-rules-1997/schedule-1/crossheading-1/paragraph-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.