diff --git a/CRAN-RELEASE b/CRAN-RELEASE
index 629d26a..c8b72f3 100644
--- a/CRAN-RELEASE
+++ b/CRAN-RELEASE
@@ -1,2 +1,2 @@
-This package was submitted to CRAN on 2021-12-01.
-Once it is accepted, delete this file and tag the release (commit a88ce56).
+This package was submitted to CRAN on 2021-12-02.
+Once it is accepted, delete this file and tag the release (commit 42b16b0).
diff --git a/R/index0.R b/R/index0.R
index afb14c6..a2d9038 100644
--- a/R/index0.R
+++ b/R/index0.R
@@ -3,6 +3,8 @@
 #' Normally R is indexed from 1, but with the special `index0` class, you can
 #' have vectors that are indexed from zero. Works both for subsetting (extraction)
 #' and (sub-)assignment.
+#' An `index0` object is just like a normal vector or matrix, but `x[i]` returns
+#' or replaces the `(i+1)`th index.
 #'
 #' Assign the class `index0` to a vector, using `as.index0()` or `index_from_0()`,
 #' then use the subset operators normally and they will be indexed from zero.
@@ -29,6 +31,18 @@
 #' m[0, 1]
 #' m[0, 1] <- 99
 #' m
+#' 
+#' @return
+#' `as.index0` returns the input (typically a vector or matrix) unchanged except
+#' for the addition of an `index0` class attribute, which enables the zero-based
+#' indexing behaviour. Use `as.index1` to remove this class again, if present.
+#' 
+#' If `x` is a zero-indexed object with class `index0`, then `x[i]` returns an
+#' appropriate subset of `x`. The returned subset is also zero-indexed.
+#' `x[i] <- value` changes the `i`th element (effectively `(i+1)`th element in
+#' ordinary R code) in place.
+#' 
+#' `is.index0(x)` returns `TRUE` if `x` is indexed from zero, otherwise `FALSE`.
 #'
 #' @source
 #' Partially inspired by this Stack Overflow answer:
diff --git a/cran-comments.md b/cran-comments.md
index 858617d..1c6e7a6 100644
--- a/cran-comments.md
+++ b/cran-comments.md
@@ -2,4 +2,5 @@
 
 0 errors | 0 warnings | 1 note
 
-* This is a new release.
+* This is (a resubmission of) a new release.
+* Details have been added to `\value` for the S3 class
diff --git a/man/index0.Rd b/man/index0.Rd
index d21aa5f..1e08afb 100644
--- a/man/index0.Rd
+++ b/man/index0.Rd
@@ -38,10 +38,24 @@ index_from_0(x)
 
 \item{value}{typically an array-like \R object of a similar class as \code{x}.}
 }
+\value{
+\code{as.index0} returns the input (typically a vector or matrix) unchanged except
+for the addition of an \code{index0} class attribute, which enables the zero-based
+indexing behaviour. Use \code{as.index1} to remove this class again, if present.
+
+If \code{x} is a zero-indexed object with class \code{index0}, then \code{x[i]} returns an
+appropriate subset of \code{x}. The returned subset is also zero-indexed.
+\code{x[i] <- value} changes the \code{i}th element (effectively \code{(i+1)}th element in
+ordinary R code) in place.
+
+\code{is.index0(x)} returns \code{TRUE} if \code{x} is indexed from zero, otherwise \code{FALSE}.
+}
 \description{
 Normally R is indexed from 1, but with the special \code{index0} class, you can
 have vectors that are indexed from zero. Works both for subsetting (extraction)
 and (sub-)assignment.
+An \code{index0} object is just like a normal vector or matrix, but \code{x[i]} returns
+or replaces the \code{(i+1)}th index.
 }
 \details{
 Assign the class \code{index0} to a vector, using \code{as.index0()} or \code{index_from_0()},