Other things related to topo data: [[,topo-method,
[[<-,topo-method, as.topo,
download.topo,
plot,topo-method, read.topo,
summary,topo-method,
topo-class, topoInterpolate,
topoWorld
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,rsk-method,
subset,sealevel-method,
subset,section-method