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Description

C99 is a residual classification for chemical and metallurgical inventions that do not fit within the more specific IPC classes C01 through C98. It serves as a catch-all category for novel or emerging technologies in chemistry and metallurgy that predate their assignment to dedicated classifications or fall outside established technical boundaries. Examiners typically use this class only after confirming that the invention cannot be reasonably accommodated in any specialized class within Section C. Use of C99 is generally discouraged as a primary classification; instead, the most technically appropriate existing class should be selected whenever feasible.