"[["(x, i, j, ...)
"[["(x, i, j, ...)
"["(x, i, j, ..., drop = TRUE)
"[["(x, i) <- value
"[["(x, i) <- value
"[["(x, i) <- value
"[["(x, i) <- value
"["(x, i) <- value
"["(x, i) <- value
"["(x, i) <- value
"["(x, i, j, ..., drop = TRUE)
"[["(x, i, j, ...)
"[["(x, i, j, ...)
"$"(x, name)
"[["(x, i) <- value
"[["(x, i) <- value
"$"(x, name) <- value
$
, the name (not alias) of the subvariable to
extractx
if extracting, otherwise x
duly modified