seg(), ggbseg()), what is the registration coverage implied by a given age range? Called by segCoverageFromYear() and ggbsegCoverageFromYear(). Here, the function simply takes the arithmetic mean of a given age range of $Cx, as returned by segMakeColumns() or ggbsegMakeColumns(). Not intended for top-level use.segCoverageFromAges(codi, agesFit)ggb()ggbgetAgesFit or user-supplied.