diff --git a/doc/common.m4 b/doc/common.m4
index 4ae37efbc..ea546ca6c 100644
--- a/doc/common.m4
+++ b/doc/common.m4
@@ -211,6 +211,22 @@ m4_define({{_LEDGER_FILE_}}, {{
 **LEDGER_FILE**
 The journal file path when not specified with `-f`.
 Default: `~/.hledger.journal` (on windows, perhaps `C:/Users/USER/.hledger.journal`).
+
+A typical value is `~/DIR/YYYY.journal`, where DIR is a version-controlled finance directory
+and YYYY is the current year. Or `~/DIR/current.journal`, where current.journal is a symbolic
+link to YYYY.journal.
+
+On Mac computers, you can set this and other environment variables in a more thorough way
+that also affects applications started from the GUI (say, an Emacs dock icon).
+Eg on MacOS Catalina I have a `~/.MacOSX/environment.plist` file containing
+```
+{
+  "LEDGER_FILE" : "~/finance/current.journal"
+}
+```
+To see the effect you may need to `killall Dock`, or reboot.
+
+
 }} )m4_dnl
 m4_dnl
 m4_dnl The _FLAGS marker is used in generating command help (see