diff --git a/R/Start.R b/R/Start.R
index 56e9491e68bc689d8d0f1105ae2eb309dbc05130..ba01959a68970d2a35c09a917ce78a75d9df04cb 100644
--- a/R/Start.R
+++ b/R/Start.R
@@ -2538,7 +2538,9 @@ Start <- function(..., # dim = indices/selectors,
                   print(file_dim)
                 }
               }
-              #????????????????
+
+              # The inner dim selector is an array in which have file dim (e.g., time = [sdate = 2, time = 4],
+              # or the inner dim doesn't go across any file dim (e.g., no time_across = 'sdate')
               if ((!is.null(file_dim) && (file_dim %in% names(selector_file_dims))) || is.null(file_dim)) {
                 if (length(sub_array_of_selectors) > 0) {
                   if (debug) {
@@ -3050,12 +3052,20 @@ Start <- function(..., # dim = indices/selectors,
                     taken_chunks <- TRUE
                   }
                 }
-              } else {  #????????????
+              } else {
+              # The inner dim goes across a file dim (e.g., time_across = 'sdate')
                 if (debug) {
                   if (inner_dim %in% dims_to_check) {
                     print("-> THE INNER DIMENSION GOES ACROSS A FILE DIMENSION.")
                   }
                 }
+                # If "<inner_dim>_across = <file_dim> + merge_across_dims = FALSE + chunk over <inner_dim>", return error because this instance is not logically correct.
+                if (chunks[[inner_dim]]["n_chunks"] > 1 & inner_dim %in% inner_dims_across_files) {
+                  stop("Chunk over dimension '", inner_dim, "' is not allowed because '",
+                       inner_dim, "' is across '",
+                       names(inner_dims_across_files)[which(inner_dim %in% inner_dims_across_files)], "'.")
+                }
+
                 if (inner_dim %in% names(dim(sub_array_of_selectors))) {
                   if (is.null(var_with_selectors_name)) {
                     if (any(na.omit(unlist(sub_array_of_selectors)) < 1) ||