1 files changed, 5 insertions, 1 deletions
diff --git a/docs/fs.md b/docs/fs.md
index 5f3ef743..eab1b00d 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -768,7 +768,11 @@ shell writes it a line at a time), and the next open starts another. The
 pane has one history, so two opens writing at once take turns in it: each
 open's first write after the other's starts a step of its own; to
 make a loop's writes one step, write `1` (an undo point here), then `0`,
-the writes, then `1` again.
+the writes, then `1` again. An open's writes in a row to one place -- an
+append to `body`, inserts going on at `data`'s address -- are held and go
+in as one edit when anything else comes (another request, the close, or
+the editor's step once they pause 20 ms), so a 10 MB write is one copy, not
+one per 8 KB piece; any read sees them.
 
 One rule for what fails: a write fails whenever what it asked for fails,
 whether it came to a `ctl` (the root's, a pane's, a column's, a pane's