Other things related to rsk data: [[,rsk-method,
  [[<-,rsk-method, as.rsk,
  plot,rsk-method, read.rsk,
  rsk-class, rskPatm,
  rskToc, rsk,
  summary,rsk-method
Other functions that subset oce objects: subset,adp-method,
  subset,adv-method,
  subset,amsr-method,
  subset,argo-method,
  subset,cm-method,
  subset,coastline-method,
  subset,ctd-method,
  subset,echosounder-method,
  subset,lobo-method,
  subset,met-method,
  subset,oce-method,
  subset,odf-method,
  subset,sealevel-method,
  subset,section-method,
  subset,topo-method