Optional list of strings matching names of elements of biglist to
subset. Default=NULL.
numvec
Optional list of numbers of elements from biglist to subset.
Default=NULL.
selfactor
A string or vector of strings indicating which elements of the
selectivity at length output to summarize. Default=c("Lsel").
selfleet
Vector of fleets for which selectivity will be summarized. NULL=all fleets. Default=NULL.
selyr
String or vector of years for which selectivity will be summarized.
NOTE: NOT CURRENTLY WORKING. Options: NULL=all years,
"min" = first year, "max" = last year. Default="min".
selgender
Vector of genders (1 and/or 2) for which selectivity will be summarized. NULL=all genders. Default=NULL.